Re: [Emc-users] How come....

[Ralph Stirling]

> (And, while we are at it, kWh is a horrible unit. What is wrong with MJ? )

kWh is ubiquitous in the US.  Our electrical bills are all based on kWh.
Just be glad we don't use horsepower-hours :-/

-- Ralph

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Re: [Emc-users] How come....

[Kirk Wallace]

On 5/19/19 5:25 PM, Bruce Layne wrote:



On 5/19/19 6:01 PM, Kirk Wallace wrote:


There are a lot of surplus Leaf batteries available. My opinion on
 these is that these were removed for warranty replacement due to 
overheating. These are air cooled and don't do well if they are 
rapid charged more than once during long trips. I am tending to 
avoid these.


I saw those Nissan Leaf batteries as related eBay links.  The price 
per energy storage looked very good.  I assumed these were some sort 
of warranty replacement batteries, but didn't search to learn the 
reason these are on the surplus market.


Vendors don't seem to be too keen on providing information on their 
batteries. Either they don't know, don't understand what they have, or 
choose not to share. BatteryHookup.com seems to be the best DIY battery 
vendor so far. My opinion on Leaf batteries is based on the RapidGate 
chatter, where rapid charging was slowed way down on the second charge 
which you don't want to learn about in the middle of a long trip.

https://www.youtube.com/watch?v=Dpwyue9IiBE


I vaguely recall hearing of technical problems with the Nissan Leaf.  If the problem was 
overheating when fast charging or discharging in a car, that

wouldn't deter me from using them in an off-the-grid home.  It
probably wouldn't be an issue in a properly sized system, and the
Nissan batteries could easily be mounted vertically with air gaps and
even inexpensive heat sinks could be used to accentuate cooling.


For properly sized stationary batteries I don't think the battery will 
come close to working hard enough to even get warm. It would be nice if 
vendors would test cells or battery capacity and post this in their ads. 
Testing is likely to be expensive so there isn't much incentive for 
testing if one is selling cells well enough anyway.




I'd need to research the cell balancing and battery management as 
that's critical.  A lot of those electronics are built into the

Tesla battery packs which sounds good, but it's proprietary so using
them in a home requires the batteries to be fooled into thinking
they're in a car.  An entrepreneur makes a device to do that.  Jack
Rickard of EVTV.


The $1200 class batteries are for a module within the battery pack, so 
it is just ~5 kWh(?) of 18650 cells and no electronics. In my view 
balancing isn't nearly as important as monitoring which is much easier 
to do with off-the-self products.




http://store.evtv.me/proddetail.php?prod=1FullpackController

I sent links earlier in this thread to a friend who used a Tesla 
battery for his off-the-grid home, and he displays battery life in 
odometer miles.  I think he largely does this for a lark and he 
displays more conventional units as well, but keeping it in terms of 
miles, even though not applicable to a house, does provide a battery 
life indication that compares well to the original automotive use. No
doubt he'll get more "miles" from his off the grid batteries than 
they'd get in a car where they're typically charged and discharged

at a faster rate.

Part 3 of the series, where the custom battery monitoring is 
demonstrated: https://www.youtube.com/watch?v=AIY2EWke-AA




On 5/19/19 6:07 PM, andy pugh wrote:
(And, while we are at it, kWh is a horrible unit. What is wrong 
with MJ? )


Kilowatt hours is easier for me to convert into miles.   :-)

An American arguing with an Englishman over the metric system is 
funny. You guys invented this crummy system.  Just because you were 
smart enough to switch to the metric system and we're still stuck on 
stupid is no call for being cheeky.   :-P


- and there is no such word as "maths".


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Re: [Emc-users] How come....

[Bruce Layne]

On 5/19/19 6:01 PM, Kirk Wallace wrote:

> There are a lot of surplus Leaf batteries available. My opinion on
> these is that these were removed for warranty replacement due to
> overheating. These are air cooled and don't do well if they are rapid
> charged more than once during long trips. I am tending to avoid these.

I saw those Nissan Leaf batteries as related eBay links.  The price per
energy storage looked very good.  I assumed these were some sort of
warranty replacement batteries, but didn't search to learn the reason
these are on the surplus market.  I vaguely recall hearing of technical
problems with the Nissan Leaf.  If the problem was overheating when fast
charging or discharging in a car, that wouldn't deter me from using them
in an off-the-grid home.  It probably wouldn't be an issue in a properly
sized system, and the Nissan batteries could easily be mounted
vertically with air gaps and even inexpensive heat sinks could be used
to accentuate cooling.

I'd need to research the cell balancing and battery management as that's
critical.  A lot of those electronics are built into the Tesla battery
packs which sounds good, but it's proprietary so using them in a home
requires the batteries to be fooled into thinking they're in a car.  An
entrepreneur makes a device to do that.  Jack Rickard of EVTV.

http://store.evtv.me/proddetail.php?prod=1FullpackController

I sent links earlier in this thread to a friend who used a Tesla battery
for his off-the-grid home, and he displays battery life in odometer
miles.  I think he largely does this for a lark and he displays more
conventional units as well, but keeping it in terms of miles, even
though not applicable to a house, does provide a battery life indication
that compares well to the original automotive use.  No doubt he'll get
more "miles" from his off the grid batteries than they'd get in a car
where they're typically charged and discharged at a faster rate.

Part 3 of the series, where the custom battery monitoring is demonstrated:
https://www.youtube.com/watch?v=AIY2EWke-AA



On 5/19/19 6:07 PM, andy pugh wrote:
> (And, while we are at it, kWh is a horrible unit. What is wrong with MJ? )

Kilowatt hours is easier for me to convert into miles.   :-)

An American arguing with an Englishman over the metric system is funny. 
You guys invented this crummy system.  Just because you were smart
enough to switch to the metric system and we're still stuck on stupid is
no call for being cheeky.   :-P








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[Emc-users] Atomic pi

[Robert Murphy]

My Atomic should be here today.

Ethernet is on the PCIe bus (if that hasn't been mentioned)

The BBB is a great platform for a compact solution but AFAIK machinekit
is the only option for PRU support. I've been running my setup for about
a year now.



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Re: [Emc-users] How come....

[Dave Cole]

Apparently you guys didn't notice that the Ebay guy selling Tesla cells 
had already sold over a hundred of those battery packs.

So I doubt he got them from crashed Teslas.
To me buying a used Lithium battery makes only a little more sense than 
buying a used Lead Acid battery.
I bet I could buy a bunch of used 6 volt golf cart batteries from the 
golf courses around me as well..
If those battery packs were $300, it would be one thing, but at $1200 
plus, I don't see that as much of a deal.


Dave

On 5/19/2019 7:10 PM, Gregg Eshelman via Emc-users wrote:

There seems to be a pretty good supply of battery packs from wrecked Tesla 
Model S cars, often with fairly low mileage. People have been taking those 
apart to shoehorn the modules and one or both motor drivetrains into various 
other vehicles. Of course by doing that they lose the crash protection of the 
aluminum battery housing. One person flipped an empty Model S battery upside 
down, attached a couple of trailer spindles and fenders and a tongue to make a 
little flatbed trailer.

I think it'd be fun to 'gassify' a Model S. Either convert the empty battery housing to a 
fuel tank or build a tank to fit in its place, then stuff some FWD drivetrain in the 
"frunk".

 On Sunday, May 19, 2019, 10:32:52 AM MDT, Dave Cole 
 wrote:
  I do have to wonder though... if these Tesla cells were no longer usable
for a Tesla, why would anyone think they would be good in a stationary
application unless they were derated by quite a bit.
$1200 is far from free.

Dave

On 5/17/2019 12:24 PM, Kirk Wallace wrote:

Here is a fairly common surplus Tesla module:


https://www.ebay.com/itm/262333679871

If these have have not been abused after they were removed from the
car they should last many thousands of deep cycles.  They are 6s but a
7th s can be added in order to cycle them deeper on a common 24 volt
system.

My system (single, living in an RV) is close to this except I am using
two Johnson Controls modules rewired as 7s:

https://www.mobile-solarpower.com/tesla-solar-battery-diy.html
https://www.ebay.com/itm/123187038180

This technology is changing so quickly that it is hard to keep current
and reviews become stale in a month or two.

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Re: [Emc-users] How come....

[Gregg Eshelman via Emc-users]

There seems to be a pretty good supply of battery packs from wrecked Tesla 
Model S cars, often with fairly low mileage. People have been taking those 
apart to shoehorn the modules and one or both motor drivetrains into various 
other vehicles. Of course by doing that they lose the crash protection of the 
aluminum battery housing. One person flipped an empty Model S battery upside 
down, attached a couple of trailer spindles and fenders and a tongue to make a 
little flatbed trailer.

I think it'd be fun to 'gassify' a Model S. Either convert the empty battery 
housing to a fuel tank or build a tank to fit in its place, then stuff some FWD 
drivetrain in the "frunk".

On Sunday, May 19, 2019, 10:32:52 AM MDT, Dave Cole 
 wrote:  
 I do have to wonder though... if these Tesla cells were no longer usable 
for a Tesla, why would anyone think they would be good in a stationary 
application unless they were derated by quite a bit.
$1200 is far from free.

Dave

On 5/17/2019 12:24 PM, Kirk Wallace wrote:
>
> Here is a fairly common surplus Tesla module:
>
>> https://www.ebay.com/itm/262333679871
>
> If these have have not been abused after they were removed from the 
> car they should last many thousands of deep cycles.  They are 6s but a 
> 7th s can be added in order to cycle them deeper on a common 24 volt 
> system.
>
> My system (single, living in an RV) is close to this except I am using 
> two Johnson Controls modules rewired as 7s:
>> https://www.mobile-solarpower.com/tesla-solar-battery-diy.html
>> https://www.ebay.com/itm/123187038180
>
> This technology is changing so quickly that it is hard to keep current 
> and reviews become stale in a month or two.  
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Re: [Emc-users] How come....

[andy pugh]

On Sun, 19 May 2019 at 22:30, Chris Albertson 
wrote:

> You just have to do a calculation,  What is the cost per KWH over the
> remaining
> life of the battery.


I am not sure that that is the correct calculation.
What really matters is that the battery is big enough for your purposes,
and then cost-per-year is more important that cost / kWh.

(And, while we are at it, kWh is a horrible unit. What is wrong with MJ? )

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] How come....

[Kirk Wallace]

On 5/19/19 9:34 AM, Dave Cole wrote:
I do have to wonder though... if these Tesla cells were no longer usable 
for a Tesla, why would anyone think they would be good in a stationary 
application unless they were derated by quite a bit.

$1200 is far from free.

Dave


My take on this is that Tesla batteries become available from wrecked 
vehicles where the car was written off, but not the battery. As far as I 
know, a Tesla battery under proper use has not worn out yet. There has 
been data on normal-use degradation but this seems to indicate that I 
will likely be dead before current batteries are.


There are a lot of surplus Leaf batteries available. My opinion on these 
is that these were removed for warranty replacement due to overheating. 
These are air cooled and don't do well if they are rapid charged more 
than once during long trips. I am tending to avoid these.


The Johnson batteries I have are said to be from an electric bus 
conversion study and were liquid cooled and likely well cared for.


So these batteries can come to the market for various reasons but for 
simply being worn out doesn't seem to be a common reason yet.



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Re: [Emc-users] Unusual help request.

[Chris Albertson]

I actually worked at a place where we needed to set up tempory networks at
military bases.  Part of out kit was a 2 km spool of fiber cable.
Yes over a mile.  It as in a shipping case with a roller and a hand crank.
  It was easy enough to handle that even untrained random
"Army guys" could deal with it ad the Ethernet over tres under highways
into a window that was a half mile away. It is completely "plug and play"
and not much harder to use than cat-5 cable.

SOme peole use WiFi with two hi-gain antennt facing each other.   For that
you need a clear line of sigh and MUCH fiddling.  Fiber
has gigabye speed and is way-easy.

On Sun, May 19, 2019 at 10:35 AM Davide <77...@tiscali.it> wrote:

> Hi, and thanks for your suggestions.
>
>
>
> The driver does support multiple ethernet cards (up to 4) so you could use
> a 7i92 (for example)  for each motor. Though even then 150m would be
> optimistic, I suspect.
>
>  why? isn't it a standard ethernet? I can plug pc eth to a good gigabit
> switch and run 4 lines to the winches, or put 2 other switches around and
> amplify the signal.
>
>
> I also have in mind to use just one 7i92 near the pc, and build a ttl ->
> fiber optic converter using SN75451 (two channel Logic + LED drivers) to
> drive some HFBR1414 plugs, which claim to transmit up to 1500 mt (minimum
> 500mt)
>
>
> I have a tech question about 7i92. I have only run Lcnc using software
> step gen, but I understand that a 7i92 does step generation on its own,
> freeing the pc from doing the hard work. But what messages are sent from
> the pc? are they just POS/SPEED? and, since I have my untrivial kinematics,
> are they always done by the pc, right?
>
> when I run a latency test I have good results, something like Servo t.
> 2-3000 and Base t. 5-7000.   Is the 7i92 driver linked to the Servo, or
> Base Thread? what Latency time is it needed? and for 4*7i92?
>
>
> I'm sorry for all these questions, but unfortunately I don't have a lot o
> f time to experiment, so I need to clarify my mind, before buying a lot of
> things..
>
>
> Thanks, Davide.
>
>
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] How come....

[Chris Albertson]

You just have to do a calculation,  What is the cost per KWH over the
remaining
life of the battery. A new power wall costs $6,700 and has 13 KWH that
can be
cycled daily for 10 years.   so 3650 days times 13KW =  47 megawat hours
for $6,700
or 14 cents per KWH.

DO the math on the used battery.  If it is much less then $0.14/KWH buy it

So if the price is $1,200 and it still can store 7,000 watt-hours and has a
5 year remaining
life it would be useless in a car but it works out to  $0.09/KWH and
would not is a truly horrible deal.

So it is possible a battery that is usless in the car could be used for a
house.  Better
is to keep the battery in thr car and use the car for short trips, less
than 100 miles. round trip

Cell become usless in a car when you reach about 1/2 capasity but if the
price per KWH is OK
they can work in a house.   FOr a house, you might need the cells for
multiple salvage cars.



On Sun, May 19, 2019 at 9:32 AM Dave Cole  wrote:

> I do have to wonder though... if these Tesla cells were no longer usable
> for a Tesla, why would anyone think they would be good in a stationary
> application unless they were derated by quite a bit.
> $1200 is far from free.
>
> Dave
>
> On 5/17/2019 12:24 PM, Kirk Wallace wrote:
> >
> > Here is a fairly common surplus Tesla module:
> >
> >> https://www.ebay.com/itm/262333679871
> >
> > If these have have not been abused after they were removed from the
> > car they should last many thousands of deep cycles.  They are 6s but a
> > 7th s can be added in order to cycle them deeper on a common 24 volt
> > system.
> >
> > My system (single, living in an RV) is close to this except I am using
> > two Johnson Controls modules rewired as 7s:
> >> https://www.mobile-solarpower.com/tesla-solar-battery-diy.html
> >> https://www.ebay.com/itm/123187038180
> >
> > This technology is changing so quickly that it is hard to keep current
> > and reviews become stale in a month or two.
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
> ___
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Semaphores, from real time --> background process

[andy pugh]

On Sun, 19 May 2019 at 08:52, Nicklas Karlsson 
wrote:

> I need a semaphore or similar to signal from periodic task initialization
> is needed. The concept of semaphores are weel known for me but in Linuxcnc
> I found several implements, ordinary posix, rt_sem, rcs_sem_t. Any idea
> which "implementation" is best to use?
>

I have no idea, but I did find this (very old) example:
https://github.com/LinuxCNC/linuxcnc/tree/master/src/rtapi/examples/semaphore



-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] Unusual help request.

[Peter C. Wallace]

On Sun, 19 May 2019, Davide wrote:


Date: Sun, 19 May 2019 20:49:07 +0200
From: Davide <77...@tiscali.it>
Reply-To: "Enhanced Machine Controller (EMC)"

To: Emc-users@lists.sourceforge.net
Subject: [Emc-users] Unusual help request.




The bob i'm using now is the keling c35, which gas buffered TTL outputs.
Maybe, since I need very High step rates (i need to reach almost max speed out 
of these hybrid nema34-12NM steppers) i'm thinking about going with 7i92.
I've read the manual and there's not the possibility to set them for 
differential output, am i right? In case i can build a simple rs422 bob.



Another possibility is 1X 7I96 which has 5X differential step/dir outputs


Yes, right now i have stretch with preempt-rt on, with lcnc 2.8. Peter, please 
can you confirm 7i92 works OK with latest 2.8? And, just in case i'll feel more 
confortable in using one 7i92 per winch and ethernet/optic fiber converters for 
the long range, i know 4 of 7i92 are really oversized, but can you confirm they 
can work together without slowing down everything?



This can work but depending on your host PC you might need to drop the servo 
thread rate to 500 Hz or so, this has no effect on the maximum step rate,

just the number of velocity steps getting to full speed

I actually think it makes more sense to have one controller and wire the 
step/dir signals the longest distance since they are the slowest, only a fwe 
hundred KHz at most. This might change if you have distributed I/O (local limit 
switches etc)



Thanks, Davide.



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Mesa Electronics

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[Emc-users] Unusual help request.

[Davide]

I'm sorry my replies are fragmented, but i have problems in setting gmail for a 
different e-mail address out... Long story.

>
>I have a tech question about 7i92. I have only run Lcnc using software step 
>gen, but I understand that a 7i92 does step generation on its own, freeing 
>the pc from doing the hard work. But what messages are sent from the pc? are 
>they just POS/SPEED? and, since I have my untrivial kinematics, are they 
>always done by the pc, right?

Yes, speed sent, current position returned, all position/velocity calculations 
done in LinuxCNC, but if you can get the desired step rates from your parallel 
port, you may not need a 7I92 and just need differential drivers at the BOB 
end for the paralle port generated step/dir signals

The bob i'm using now is the keling c35, which gas buffered TTL outputs.
Maybe, since I need very High step rates (i need to reach almost max speed out 
of these hybrid nema34-12NM steppers) i'm thinking about going with 7i92.
I've read the manual and there's not the possibility to set them for 
differential output, am i right?
In case i can build a simple rs422 bob.

>
>when I run a latency test I have good results, something like Servo t. 2-3000 
>and Base t. 5-7000.  Is the 7i92 driver linked to the Servo, or Base Thread? 
>what Latency time is it needed? and for 4*7i92?
>

The 7I92 uses a servo thread only and requires a Preempt-RT kernel (the 
Stretch test ISO is the easiet way to do this)


Yes, right now i have stretch with preempt-rt on, with lcnc 2.8.
Peter, please can you confirm 7i92 works OK with latest 2.8?
And, just in case i'll feel more confortable in using one 7i92 per winch and 
ethernet/optic fiber converters for the long range, i know 4 of 7i92 are really 
oversized, but can you confirm they can work together without slowing down 
everything?

Thanks, Davide.

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Re: [Emc-users] Unusual help request.

[Peter C. Wallace]

On Sun, 19 May 2019, Davide wrote:


Date: Sun, 19 May 2019 19:33:51 +0200
From: Davide <77...@tiscali.it>
Reply-To: "Enhanced Machine Controller (EMC)"

To: Emc-users@lists.sourceforge.net
Subject: [Emc-users] Unusual help request.

Hi, and thanks for your suggestions.




The driver does support multiple ethernet cards (up to 4) so you could use a 
7i92 (for example)  for each motor. Though even then 150m would be 
optimistic, 
I suspect.


why? isn't it a standard ethernet? I can plug pc eth to a good gigabit switch 
and run 4 lines to the winches, or put 2 other switches around and amplify 
the signal.




Standard Ethernet maximum length is 100M



I also have in mind to use just one 7i92 near the pc, and build a ttl -> 
fiber 
optic converter using SN75451 (two channel Logic + LED drivers) to drive some 
HFBR1414 plugs, which claim to transmit up to 1500 mt (minimum 500mt)



Fiber optics is not needed unless you have MHz step rates, RS-422 differential
should be fine up to a few hundred KHz step rates, and may not even need any 
added hardware other than chosing a BOB with differential outputs and possible 
reverse polarity protection if you are using low end drives





I have a tech question about 7i92. I have only run Lcnc using software step 
gen, but I understand that a 7i92 does step generation on its own, freeing 
the pc from doing the hard work. But what messages are sent from the pc? are 
they just POS/SPEED? and, since I have my untrivial kinematics, are they 
always done by the pc, right?


Yes, speed sent, current position returned, all position/velocity calculations 
done in LinuxCNC, but if you can get the desired step rates from your parallel 
port, you may not need a 7I92 and just need differential drivers at the BOB 
end for the paralle port generated step/dir signals




when I run a latency test I have good results, something like Servo t. 2-3000 
and Base t. 5-7000.  Is the 7i92 driver linked to the Servo, or Base Thread? 
what Latency time is it needed? and for 4*7i92?




The 7I92 uses a servo thread only and requires a Preempt-RT kernel (the 
Stretch test ISO is the easiet way to do this)





I'm sorry for all these questions, but unfortunately I don't have a lot o f 
time to experiment, so I need to clarify my mind, before buying a lot of 
things..



Thanks, Davide.


Peter Wallace
Mesa Electronics

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[Emc-users] Unusual help request.

[Davide]

Hi, and thanks for your suggestions.

 

The driver does support multiple ethernet cards (up to 4) so you could use
a 7i92 (for example)  for each motor. Though even then 150m would be
optimistic, I suspect.

 why? isn't it a standard ethernet? I can plug pc eth to a good gigabit switch 
and run 4 lines to the winches, or put 2 other switches around and amplify the 
signal.


I also have in mind to use just one 7i92 near the pc, and build a ttl -> fiber 
optic converter using SN75451 (two channel Logic + LED drivers) to drive some 
HFBR1414 plugs, which claim to transmit up to 1500 mt (minimum 500mt)


I have a tech question about 7i92. I have only run Lcnc using software step 
gen, but I understand that a 7i92 does step generation on its own, freeing the 
pc from doing the hard work. But what messages are sent from the pc? are they 
just POS/SPEED? and, since I have my untrivial kinematics, are they always done 
by the pc, right?

when I run a latency test I have good results, something like Servo t. 2-3000 
and Base t. 5-7000.   Is the 7i92 driver linked to the Servo, or Base Thread? 
what Latency time is it needed? and for 4*7i92?


I'm sorry for all these questions, but unfortunately I don't have a lot o f 
time to experiment, so I need to clarify my mind, before buying a lot of 
things..


Thanks, Davide.


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Re: [Emc-users] Unusual help request.

[Peter C. Wallace]

On Sun, 19 May 2019, Nicklas Karlsson wrote:


Date: Sun, 19 May 2019 18:27:44 +0200
From: Nicklas Karlsson 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] Unusual help request.


On Sun, 19 May 2019, Davide wrote:


Date: Sun, 19 May 2019 16:26:26 +0200
From: Davide <77...@tiscali.it>
Reply-To: "Enhanced Machine Controller (EMC)"

To: Emc-users@lists.sourceforge.net
Subject: [Emc-users] Unusual help request.

Hi, I have a strange setup to solve. So I'm asking you an help, on the top
of your knowledge (sorry for any language mistake) Some time ago I have
built an inverted wire tetrapod, which was made by 4 winches placed at a max
distance of 20 meters one each other in a rectangular shape. So until now it
was ok to have a 48v 20A DC power supply and a parallel bob near my pc (an
asrock q1900b-itx), and transmit step/dir signals thru ethernet cables to
the stepper drivers inside the winches.

Now I have to modify that to make a very little object fly inside a soccer
arena, so the motors will be placed at 80 meters one each other, and i'm
really worried that a step every 10 will arrive to the drivers, if any at
all.. The further motor will be at 150mt if I'm lucky..

An idea can be a mesa ethernet card, but I should use 4 of them, so I'm
asking you if you think is possible to make 4 of them work with linuxcnc?

Another can be convert in some way step dir signals to optic fiber
transport. But i couldn't find anything to buy.

Any other suggestion?
Thanks, Davide.




150 meters is no problem for 100 KHz RS-422 (Spec is 1220 meters at 100 KBPS
~= 50K steps/second) So just using good line drivers/ receivers should be fine
It may even work with differential drivers and normal opto-isolated step motor
drives driven differentially


You might also need terminators to avoid reflections.


Yes, you probably need to know the drives optopcoupler input circuitry

Many Chinese drives get this wrong (no reverse polarity protection diode 
across OPTO LED) In this case, an external reverse diode/resistor pair would 
handle the reverse direction oveshoot and prevent OPTO damage in the OPTO LED 
off direction


Many drives have 220 ohm series resistors, this would result in less than 50% 
overshoot (for say 750 ns with 150 meters ) which should not be harmfull in 
the on direction



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Peter Wallace
Mesa Electronics

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Re: [Emc-users] How come....

[Dave Cole]

That's what I understood...  I won't be owning a Tesla until that changes.
Dave

On 5/18/2019 2:50 PM, Bruce Layne wrote:

Tesla has adopted the software
rental model where the customer doesn't really own anything.



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Re: [Emc-users] How come....

[Dave Cole]

I do have to wonder though... if these Tesla cells were no longer usable 
for a Tesla, why would anyone think they would be good in a stationary 
application unless they were derated by quite a bit.

$1200 is far from free.

Dave

On 5/17/2019 12:24 PM, Kirk Wallace wrote:


Here is a fairly common surplus Tesla module:


https://www.ebay.com/itm/262333679871


If these have have not been abused after they were removed from the 
car they should last many thousands of deep cycles.  They are 6s but a 
7th s can be added in order to cycle them deeper on a common 24 volt 
system.


My system (single, living in an RV) is close to this except I am using 
two Johnson Controls modules rewired as 7s:

https://www.mobile-solarpower.com/tesla-solar-battery-diy.html
https://www.ebay.com/itm/123187038180


This technology is changing so quickly that it is hard to keep current 
and reviews become stale in a month or two.



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Re: [Emc-users] How come....

[Dave Cole]

I do have to wonder though... if these Tesla cells were no longer usable 
for a Tesla, why would anyone think they would be good in a stationary 
application unless they were derated by quite a bit.

$1200 is far from free.

Dave

On 5/17/2019 12:24 PM, Kirk Wallace wrote:


Here is a fairly common surplus Tesla module:


https://www.ebay.com/itm/262333679871


If these have have not been abused after they were removed from the 
car they should last many thousands of deep cycles.  They are 6s but a 
7th s can be added in order to cycle them deeper on a common 24 volt 
system.


My system (single, living in an RV) is close to this except I am using 
two Johnson Controls modules rewired as 7s:

https://www.mobile-solarpower.com/tesla-solar-battery-diy.html
https://www.ebay.com/itm/123187038180


This technology is changing so quickly that it is hard to keep current 
and reviews become stale in a month or two.



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Re: [Emc-users] Unusual help request.

[Nicklas Karlsson]

> On Sun, 19 May 2019, Davide wrote:
> 
> > Date: Sun, 19 May 2019 16:26:26 +0200
> > From: Davide <77...@tiscali.it>
> > Reply-To: "Enhanced Machine Controller (EMC)"
> > 
> > To: Emc-users@lists.sourceforge.net
> > Subject: [Emc-users] Unusual help request.
> > 
> > Hi, I have a strange setup to solve. So I'm asking you an help, on the top 
> > of your knowledge (sorry for any language mistake) Some time ago I have 
> > built an inverted wire tetrapod, which was made by 4 winches placed at a 
> > max 
> > distance of 20 meters one each other in a rectangular shape. So until now 
> > it 
> > was ok to have a 48v 20A DC power supply and a parallel bob near my pc (an 
> > asrock q1900b-itx), and transmit step/dir signals thru ethernet cables to 
> > the stepper drivers inside the winches.
> >
> > Now I have to modify that to make a very little object fly inside a soccer 
> > arena, so the motors will be placed at 80 meters one each other, and i'm 
> > really worried that a step every 10 will arrive to the drivers, if any at 
> > all.. The further motor will be at 150mt if I'm lucky..
> >
> > An idea can be a mesa ethernet card, but I should use 4 of them, so I'm 
> > asking you if you think is possible to make 4 of them work with linuxcnc?
> >
> > Another can be convert in some way step dir signals to optic fiber 
> > transport. But i couldn't find anything to buy.
> >
> > Any other suggestion?
> > Thanks, Davide.
> >
> 
> 
> 150 meters is no problem for 100 KHz RS-422 (Spec is 1220 meters at 100 KBPS 
> ~= 50K steps/second) So just using good line drivers/ receivers should be fine
> It may even work with differential drivers and normal opto-isolated step 
> motor 
> drives driven differentially

You might also need terminators to avoid reflections.


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Re: [Emc-users] Unusual help request.

[Nicklas Karlsson]

On Sun, 19 May 2019 08:47:42 -0700
"John Dammeyer"  wrote:

> What's the maximum step rate you are using?   Depending on the rate you can 
> probably use either RS485 drivers/receivers or CAN bus transceivers. The 
> RS485 is true differential while the CAN bus is pseudo differential relative 
> to ground but good to 1Mbps.
> 
> In both cases, inside shielded twisted pair, those distances aren't a big 
> issue.CAN bus drivers require 120 Ohm impedance cable.   RS485 can use 
> cheaper 100 Ohm impedance cable.  Properly terminating each end with the 
> cable impedance (120 Ohm at each end for CAN, 100 Ohm at each end for RS485) 
> will result in a clean step/dir set of signals.

In doubt about requirements on cable impedance. For CAN bus drivers there 
should 120ohm terminator resistor on both ends. RS-485 is a little bit diffent, 
you most certainly find if you search on internet.


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Re: [Emc-users] Unusual help request.

[andy pugh]

On Sun, 19 May 2019 at 16:49, John Dammeyer  wrote:

>
> You could even use the Ethernet Cable with RS485.  That would be my first
> try.Those sorts of distances are run all the time for DMX-512A light
> show controls with a bit rate of 500kbps.
>

DMX cable might be worth looking at for the links too.
https://www.ebay.co.uk/itm/151037897894

I wonder if there would be an advantage in running quadrature step control,
rather than step/dir. It has a lower effectuve bit-rate, and better noise
immunity.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] How come.... --> battery safety due to high current, DC relay

[Nicklas Karlsson]

> > For safety I learned relays fail open circuit while MOSFETs fail short
> > circuited, I also experienced MOSFET short circuit failure. Happen to
> > know anything more about this?
> >
> It is for this reason that higher current dc loads, which will often be 
> inductive are often of the t-bar design. The armature, when released 
> will rise and hit the crossbar contact with enough force to break the 
> microweld, but even that isn't trusted, so I've seen circuits that used 
> a 4 pole contactor with all 4 poles in series.

Tried two in series with buzzing sound sometimes but do not care to much about 
it since it's only temporary.

Maybe AC is a better choice then using relays?

> I'm sure you've all seen the familiar flywheel diode placed across the 
> relay coil to prevent the inductive spike when turning off the relay, 
> from rising more than a volt or two above the supply voltage, it is 
> absorbing the relay coils currant during the turn off period, preventing 
> the transistor from being over voltaged by the inductance and punched 
> thru for a permanent short.

Yes I also added this diode for myself.

> This also delays the relays release by a 
> few milliseconds. If controlled by a relay, the circuit should be 
> expected to have a few milliseconds of lag anyway.

How fast current decrease depend on resistance and should be possible to make 
this time shorter by for example adding zener diode or resistor in series with 
diode with a higher but limited turn off voltage spike.

> Modern mosfets can often withstand 1000 volts or more for short periods 
> of time, so a lot of research has gone into mosfet _drivers_ to do 2 
> things, 1st being to switch it as fast as possible to reduce its heat 
> dissipation during the transition,

This is indeed important for low switching losses.

> and 2nd to get the opposite side of a 
> switching circuit turned on just slow enough you don't have a short 
> because both sides are on at the same time, but you must get the 
> opposite side turned on with a minimum of dead time between them to 
> short circuit the voltage stress on the one just turned off. 5ns can 
> make or destroy in this case. The diff is that it works for decades, or 
> you break the mirror and let all the smoke out.

The dead time may add some voltage distortion and some devices have lower 
voltage drop then turned on, otherwise current is thru free wheeling diode.


Nicklas Karlsson


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Re: [Emc-users] Unusual help request.

[John Dammeyer]

What's the maximum step rate you are using?   Depending on the rate you can 
probably use either RS485 drivers/receivers or CAN bus transceivers. The RS485 
is true differential while the CAN bus is pseudo differential relative to 
ground but good to 1Mbps.

In both cases, inside shielded twisted pair, those distances aren't a big 
issue.CAN bus drivers require 120 Ohm impedance cable.   RS485 can use 
cheaper 100 Ohm impedance cable.  Properly terminating each end with the cable 
impedance (120 Ohm at each end for CAN, 100 Ohm at each end for RS485) will 
result in a clean step/dir set of signals.

You could even use the Ethernet Cable with RS485.  That would be my first try.  
  Those sorts of distances are run all the time for DMX-512A light show 
controls with a bit rate of 500kbps.

John Dammeyer

"ELS! Nothing else works as well for your Lathe"
Automation Artisans Inc.
www.autoartisans.com




> -Original Message-
> From: Davide [mailto:77...@tiscali.it]
> Sent: May-19-19 7:26 AM
> To: Emc-users@lists.sourceforge.net
> Subject: [Emc-users] Unusual help request.
> 
> Hi, I have a strange setup to solve. So I'm asking you an help, on the top of
> your knowledge (sorry for any language mistake)
> Some time ago I have built an inverted wire tetrapod, which was made by 4
> winches placed at a max distance of 20 meters one each other in a
> rectangular shape.
> So until now it was ok to have a 48v 20A DC power supply and a parallel bob
> near my pc (an asrock q1900b-itx), and transmit step/dir signals thru
> ethernet cables to the stepper drivers inside the winches.
> 
> Now I have to modify that to make a very little object fly inside a soccer
> arena, so the motors will be placed at 80 meters one each other, and i'm
> really worried that a step every 10 will arrive to the drivers, if any at 
> all.. The
> further motor will be at 150mt if I'm lucky..
> 
> An idea can be a mesa ethernet card, but I should use 4 of them, so I'm
> asking you if you think is possible to make 4 of them work with linuxcnc?
> 
> Another can be convert in some way step dir signals to optic fiber transport.
> But i couldn't find anything to buy.
> 
> Any other suggestion?
> Thanks, Davide.
> 
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Re: [Emc-users] Unusual help request.

[Peter C. Wallace]

On Sun, 19 May 2019, Davide wrote:


Date: Sun, 19 May 2019 16:26:26 +0200
From: Davide <77...@tiscali.it>
Reply-To: "Enhanced Machine Controller (EMC)"

To: Emc-users@lists.sourceforge.net
Subject: [Emc-users] Unusual help request.

Hi, I have a strange setup to solve. So I'm asking you an help, on the top 
of your knowledge (sorry for any language mistake) Some time ago I have 
built an inverted wire tetrapod, which was made by 4 winches placed at a max 
distance of 20 meters one each other in a rectangular shape. So until now it 
was ok to have a 48v 20A DC power supply and a parallel bob near my pc (an 
asrock q1900b-itx), and transmit step/dir signals thru ethernet cables to 
the stepper drivers inside the winches.


Now I have to modify that to make a very little object fly inside a soccer 
arena, so the motors will be placed at 80 meters one each other, and i'm 
really worried that a step every 10 will arrive to the drivers, if any at 
all.. The further motor will be at 150mt if I'm lucky..


An idea can be a mesa ethernet card, but I should use 4 of them, so I'm 
asking you if you think is possible to make 4 of them work with linuxcnc?


Another can be convert in some way step dir signals to optic fiber 
transport. But i couldn't find anything to buy.


Any other suggestion?
Thanks, Davide.




150 meters is no problem for 100 KHz RS-422 (Spec is 1220 meters at 100 KBPS 
~= 50K steps/second) So just using good line drivers/ receivers should be fine
It may even work with differential drivers and normal opto-isolated step motor 
drives driven differentially





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Mesa Electronics



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Re: [Emc-users] Unusual help request.

[andy pugh]

On Sun, 19 May 2019 at 15:28, Davide <77...@tiscali.it> wrote:

>
> Now I have to modify that to make a very little object fly inside a soccer
> arena, so the motors will be placed at 80 meters one each other, and i'm
> really worried that a step every 10 will arrive to the drivers, if any at
> all.. The further motor will be at 150mt if I'm lucky..
>

I was going to suggest smart-serial (and possibly a set of STMBL drives)
but that has a maximum cable length of 30m.

An idea can be a mesa ethernet card, but I should use 4 of them, so I'm
> asking you if you think is possible to make 4 of them work with linuxcnc?


The driver does support multiple ethernet cards (up to 4) so you could use
a 7i92 (for example)  for each motor. Though even then 150m would be
optimistic, I suspect.

Another can be convert in some way step dir signals to optic fiber
> transport. But i couldn't find anything to buy.
>

EtherCAT might be an option.

General Mechatronics might have something suitable too.
https://www.generalmechatronics.com/en/our-products/linuxcnc

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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[Emc-users] Unusual help request.

[Davide]

Hi, I have a strange setup to solve. So I'm asking you an help, on the top of 
your knowledge (sorry for any language mistake)
Some time ago I have built an inverted wire tetrapod, which was made by 4 
winches placed at a max distance of 20 meters one each other in a rectangular 
shape.
So until now it was ok to have a 48v 20A DC power supply and a parallel bob 
near my pc (an asrock q1900b-itx), and transmit step/dir signals thru ethernet 
cables to the stepper drivers inside the winches. 

Now I have to modify that to make a very little object fly inside a soccer 
arena, so the motors will be placed at 80 meters one each other, and i'm really 
worried that a step every 10 will arrive to the drivers, if any at all.. The 
further motor will be at 150mt if I'm lucky..

An idea can be a mesa ethernet card, but I should use 4 of them, so I'm asking 
you if you think is possible to make 4 of them work with linuxcnc?

Another can be convert in some way step dir signals to optic fiber transport. 
But i couldn't find anything to buy.

Any other suggestion?
Thanks, Davide.

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Re: [Emc-users] How come.... --> battery safety due to high current, DC relay

[Gene Heskett]

On Sunday 19 May 2019 03:43:45 am Nicklas Karlsson wrote:

> On Fri, 17 May 2019 20:23:57 +1000
>
> Erik Christiansen  wrote:
> > On 16.05.19 21:18, Nicklas Karlsson wrote:
> > > > ...
> > > > I'd put the battery bank in an outbuilding.  If something shorts
> > > > out and the battery bank melts down, the little building may
> > > > burn but my house won't.
> > >
> > > There certainly is a lot of power from a byttery and it could be a
> > > little bit hard to turn off. You put a fuse at battery cable?
> >
> > If local regulations do not require a HRC (High Rupture Capacity)
> > fuse between the battery bank and any connection to it, then it's an
> > invitation to disaster. A dc arc is much more difficult to
> > extinguish, because there are no zero crossings, and molten metal
> > can end up flowing on the floor.
>
> I got the feeling DC arc is much hard to extinguish but found no good
> information about it. Then reading about how welding should be done
> and EDM I learned then air i ionized resistance get lower, in practice
> I know it is often hard to ignite the weld while it work for some
> distance then lit. I suspect and get the feeling then welding not the
> least from the ignition problem some distance could be kept then lit
> distance to keep air ionized depend on current, happen to anything
> about this?
>
> > Small HRC fuses are generally in ceramic tubes, and are sand-filled,
> > to quench the arc when the element fuses. The one I have on the desk
> > beside me is a 100 A with a 100 kA (100,000 A) arc rupture capacity,
> > but it's 27x44x49 mm, and is overkill. Just 10 times AH rating seems
> > to be normal, i.e. 2000 A rupture capacity for a 200 AH bank. (The
> > fault current will be limited by battery internal resistance.)
> >
> > > I also think DC relays have to be a little bit different than AC
> > > relays, used an ordinary AC relay for a few few days connected to
> > > a DC voltage and even though two switches is connected in series
> > > it sometimes make a buzzing sound then turned off.
> >
> > Most relays and switches are marked with both AC and DC current
> > ratings. The DC rating is always much lower, due to the difficulty
> > of rupturing a DC arc. Rather than bother with
> > maintenance/replacement due to contact deterioration after many
> > switching cycles, I prefer to switch DC loads with MOSFETs - they're
> > easy to parallel, as the inherently share.
>
> Agree, as is evindent furher up in message.
>
> For safety I learned relays fail open circuit while MOSFETs fail short
> circuited, I also experienced MOSFET short circuit failure. Happen to
> know anything more about this?
>
It is for this reason that higher current dc loads, which will often be 
inductive are often of the t-bar design. The armature, when released 
will rise and hit the crossbar contact with enough force to break the 
microweld, but even that isn't trusted, so I've seen circuits that used 
a 4 pole contactor with all 4 poles in series.

I'm sure you've all seen the familiar flywheel diode placed across the 
relay coil to prevent the inductive spike when turning off the relay, 
from rising more than a volt or two above the supply voltage, it is 
absorbing the relay coils currant during the turn off period, preventing 
the transistor from being over voltaged by the inductance and punched 
thru for a permanent short.  This also delays the relays release by a 
few milliseconds. If controlled by a relay, the circuit should be 
expected to have a few milliseconds of lag anyway.

Modern mosfets can often withstand 1000 volts or more for short periods 
of time, so a lot of research has gone into mosfet _drivers_ to do 2 
things, 1st being to switch it as fast as possible to reduce its heat 
dissipation during the transition, and 2nd to get the opposite side of a 
switching circuit turned on just slow enough you don't have a short 
because both sides are on at the same time, but you must get the 
opposite side turned on with a minimum of dead time between them to 
short circuit the voltage stress on the one just turned off. 5ns can 
make or destroy in this case. The diff is that it works for decades, or 
you break the mirror and let all the smoke out.

> Regard Nicklas Karlsson
>
>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 



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[Emc-users] Semaphores, from real time --> background process

[Nicklas Karlsson]

I need a semaphore or similar to signal from periodic task initialization is 
needed. The concept of semaphores are weel known for me but in Linuxcnc I found 
several implements, ordinary posix, rt_sem, rcs_sem_t. Any idea which 
"implementation" is best to use?


Nicklas Karlsson


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Re: [Emc-users] How come.... --> battery safety due to high current, DC relay

[Nicklas Karlsson]

On Fri, 17 May 2019 20:23:57 +1000
Erik Christiansen  wrote:

> On 16.05.19 21:18, Nicklas Karlsson wrote:
> > > ...
> > > I'd put the battery bank in an outbuilding.  If something shorts out and 
> > > the battery bank melts down, the little building may burn but my house 
> > > won't.
> > 
> > There certainly is a lot of power from a byttery and it could be a
> > little bit hard to turn off. You put a fuse at battery cable?
> 
> If local regulations do not require a HRC (High Rupture Capacity) fuse
> between the battery bank and any connection to it, then it's an
> invitation to disaster. A dc arc is much more difficult to extinguish,
> because there are no zero crossings, and molten metal can end up flowing
> on the floor.

I got the feeling DC arc is much hard to extinguish but found no good 
information about it. Then reading about how welding should be done and EDM I 
learned then air i ionized resistance get lower, in practice I know it is often 
hard to ignite the weld while it work for some distance then lit. I suspect and 
get the feeling then welding not the least from the ignition problem some 
distance could be kept then lit distance to keep air ionized depend on current, 
happen to anything about this?

> Small HRC fuses are generally in ceramic tubes, and are sand-filled, to
> quench the arc when the element fuses. The one I have on the desk beside
> me is a 100 A with a 100 kA (100,000 A) arc rupture capacity, but it's
> 27x44x49 mm, and is overkill. Just 10 times AH rating seems to be normal,
> i.e. 2000 A rupture capacity for a 200 AH bank. (The fault current will
> be limited by battery internal resistance.)
> 
> > I also think DC relays have to be a little bit different than AC
> > relays, used an ordinary AC relay for a few few days connected to a DC
> > voltage and even though two switches is connected in series it
> > sometimes make a buzzing sound then turned off.
> 
> Most relays and switches are marked with both AC and DC current ratings.
> The DC rating is always much lower, due to the difficulty of rupturing a
> DC arc. Rather than bother with maintenance/replacement due to contact
> deterioration after many switching cycles, I prefer to switch DC loads
> with MOSFETs - they're easy to parallel, as the inherently share.

Agree, as is evindent furher up in message.

For safety I learned relays fail open circuit while MOSFETs fail short 
circuited, I also experienced MOSFET short circuit failure. Happen to know 
anything more about this?


Regard Nicklas Karlsson


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