On Tue, 8 Jan 2013, Viesturs L?cis wrote: > Date: Tue, 8 Jan 2013 20:03:47 +0200 > From: "[UTF-8] Viesturs L?cis" <[email protected]> > Reply-To: "Enhanced Machine Controller (EMC)" > <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Subject: Re: [Emc-users] LinuxCNC craziness > > 2013/1/8 Peter C. Wallace <[email protected]>: >> >> Sounds like you have a severe noise issues, which is not terribly surprising >> with 11M motor cables. >> >> First thing I would do would be to add a common mode choke around the U/V/W >> Motor wires at each 7I39 end of the motor cable: Laird-Signal Integrity >> Products 28B1122-100 is a good choice here. > > Ok, I will try to find some place, where to obtain ferrite rings. One > shop did not have them, the others were already closed, so I will try > them tomorrow morning. I guess that visiting places that fix different > electronics stuff also might work - they might have something to pull > these things out, so I will try my luck finding some of them as well.
These can often be reclaimed from old CRT video cables If you are desperate > >> Another thing to do is increase the encoder filtering if you have not already >> done this: >> >> See the hostmot2 manual page, raw mode section (you need to enable >> raw-mode) >> >> Don't know if there's a HAL example of using raw-write but here's an >> approximation: >> >> setp hm2_[HOSTMOT2](BOARD).0.write-address 13312 # (0x3400) >> setp hm2_[HOSTMOT2](BOARD).0.write-data 8 (divide/10) >> setp hm2_[HOSTMOT2](BOARD).0.write-strobe TRUE > > I added enable_raw to config string right after number of encoder > modules to be loaded in top of ini file and copied the above 3 lines > in main HAL file. The thing is that I receive error message that pin > hm2_5i23.0.write-address is not found. I tried also write_address > instead of write-address, but still the same. Any ideas? Not sure, so you have enable_raw in the config string? in that case write_address should be available They are underlines at least in the manual I will verify this here > > The encoder has 4000 PPR and motor will not spin faster than 50 > revolutions per second, so that is 200 kHz max count rate. I guess > that adding a little safety margin would be smart, so what write_data > value I need to set filter time constant at 6 usec? divide by 20 which is a register value of 18 > > > >> Other things >> >> Shielded motor wires > > Not implemented. I did not find any 4-lead multistrand wires with > shielding, where each lead would be at least 0.5 mm^2. So I went for > unshielded 0.75 mm^2 4-lead wires. > > What is the idea behind it? To prevent noise being induced in motor > wires or to keep noise being induced by the current in motor wires? I > mean - keep the noise out of motor wires or keep it inside and not let > out? The shielding prevents mainly electrostatic coupling (via capacitance) from motor PWM (28V square wave) to encoder and Hall signals > >> shielded encoder cables (differential signals on twisted pairs) shield >> terminated at 7I39 (differential adapter) end and open at motor end > > Both of them are implemented - encoder signal is differential, cable > is shielded, connected to ground on a clamp right on case of control > box - that is the point, where all the ground wires meet. The encoder shield should not be terminated at the encoder end > > >> Forgot to say: the Hall wires should also be shielded >> and since they are single ended you may need to add a >> .1 uF capacitor from each Hall pin to Gnd at the 7I39 end >> of the cable > > It already has a shield - they are share the same cable with encoder signals. > I will try to find a place to obtain capacitors. > > > 2013/1/8 Bruce Layne <[email protected]>: >> The first thing I'd do is get a digital storage >> oscilloscope and observe all of the signals - motor power, Hall effect >> signals, encoder signals, any control signals. > > I have been thinking about purchase of oscilloscope for a long time. > So far their pricing have seemed too much for me, so I have not > obtained it and unfortunately have insufficient funds to do it now. > Thanks for the reminder though! I guess that having oscilloscope would > allow me to see, where exactly the noise is - is it hall signal, > encoder or whatever else... > > -- > Viesturs > > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > ------------------------------------------------------------------------------ > Master SQL Server Development, Administration, T-SQL, SSAS, SSIS, SSRS > and more. Get SQL Server skills now (including 2012) with LearnDevNow - > 200+ hours of step-by-step video tutorials by Microsoft MVPs and experts. > SALE $99.99 this month only - learn more at: > http://p.sf.net/sfu/learnmore_122512 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Master SQL Server Development, Administration, T-SQL, SSAS, SSIS, SSRS and more. Get SQL Server skills now (including 2012) with LearnDevNow - 200+ hours of step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only - learn more at: http://p.sf.net/sfu/learnmore_122512 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
