One problem is that the interpreter is asynchronous to the execution. I believe
that someone (Alex Joni, perhaps) added something to allow you to make sure
that the output had caught up with the interpreter. Off hand, I don't remember
what that was.
Ken
----- Original Message -----
From: Roland Jollivet
To: Enhanced Machine Controller (EMC)
Sent: Friday, November 30, 2007 11:48 AM
Subject: Re: [Emc-users] rs232 output
Hi
I've had this idea for a while, as I posted on other cnc lists.
The proposal is to add, probably two lines of code, to echo every character,
as the G-code file is processed, to the serial port, unconditionally.
Using 232, or 232>>485 multidrop, you could have as many devices as you want,
sitting on the line, listening/waiting for their command.
You could even embed things like 'turn on the kettle' within a comment.
Basically all non time-critical things could be controlled with this method,
freeing up valuable I/O.
You could then use a single parport line setup for all or any device to tug
low, as an Ack, using a wait or pause command in G-code, rather than processing
232 in.
It also allows one to implement any complex command that might be outside the
scope of EMC, without affecting the G-code program.
Of course, each function requires an embedded processor to implement it, but
one pic could easily manage 15 solenoids/pumps/tools.
Roland
On 30/11/2007, Jeff Epler <[EMAIL PROTECTED]> wrote:
On Fri, Nov 30, 2007 at 01:27:11AM -0800, Klemen Dovrtel wrote:
> Is it possible to send a simple command to rs232
> within the G code using emc. I would like to control
> the pneumatic valves and some other simple stuff and i
> don't want to sped parallel port pins for simple
> things like this.
Every "serial" device is different, so to do this you will have to write
your own "HAL component". If the control does not need to be real-time,
then it is fairly simple to do this. One choice is to use Python and
pyserial.
You will have to install the pyserial package. If your Ubuntu system is
on the internet, this can be done through the package manager by
selecting the package called 'python-serial'. It is in the "universe"
repository, which is not enabled by default but you can find
instructions online for how to enable it. If you're not online, then
download this file onto a usb drive then install it by double-clicking:
http://us.archive.ubuntu.com/ubuntu/pool/universe/p/pyserial/python-serial_2.2-1_all.deb
Here is an (untested!) example which should give you a general idea of
the complexity of such a driver. This driver controls a hypothetical
serial-attached device which turns something on when the character "1"
is received, and turns it off when the character "0" is received:
#!/usr/bin/python
# -----------------------------------------------------------------------
# Import the necessary modules
import hal
import time
import pyserial
# Get the serial connection -- first port, 9600,8,N,1
import serial
ser = serial.Serial(0)
# Create the HAL component and its pin. You will use a .hal file to
# connect whatever bit signal you want to the pin ' example.enable'.
h = hal.component("example")
h.newpin("enable", hal.HAL_BIT, hal.HAL_IN)
h.ready()
# The previous value of the 'enable' pin so that a byte is only sent on
# the serial port when it is necessary. This setting, which is not a
# number, means that the first time the value will always be considered
# "changed".
last = None
# (without try/except, the component will print what looks like an error
# when emc is shut down, and the cleanup below won't happen)
try:
while 1:
# As long as the component is running, periodically check
# whether the value has changed; if it has, send a command to
# set the new value
new = h["enable"]
if new != old:
if new: ser.write("1")
else: ser.write("0")
old = new
time.sleep(.01)
except KeyboardInterrupt: pass
# Shut down the connected device at exit
ser.write("0")
# -----------------------------------------------------------------------
Put the above in a file named "example", make it executable (chmod +x
example), and put it in a directory on your $PATH.
In your HAL file, hook it up something like this:
loadusr -W example
net coolant iocontrol.0.coolant-mist => example.enable
Jeff
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