Here's a summary of my setup:
- 3 axis CNC, controllable via a python script running on raspberry pi
- Windows PC can connect to the pi can run a script
The end goal is for a UI made in C# to initiate an automated test cycle for the CNC to run in. In the python program there is a Cnc object that stores the devices current position and contains methods to position it to a certain place.
The problem is if i run a new script every time i want to move the CNC, I have to re initialize the Cnc instance and it will forget it's position. So I'm wondering if I can have one master program running that contains the one and only Cnc instance, then when the remote machine wants to tell the CNC to move it can run a different script with argz for the new position python action.py x y z. This script could then communicate to the master program to call the move method to the appropriate location without ever having to re-construct a new Cnc object.
Then ideally the master program would indicate when the motion is completed and send back a message to the "action" script, that script would output something to tell the remote system that the action is completed, then it would exit, ready to be called again with new argz.
In the end the remote system is highly abstracted from any of the working and just needs to start running the master, then run the move script with argz any time it wants to perform a motion.
Note: My other idea was to just save a text file with the current position then always re initialize the instance with the info in the file.
EDIT: SOLVED... sort of
handler.py
The handler will continuously read from a text file named input.txt looking for a new integer. If received it will update a text file named output.txt to read '0', then do some action with the input (i.e move a cnc) then write the value '1' to output.txt.
from time import sleep
cur_pos=0
while True:
with open("input.txt","r") as f:
pos=f.readline()
try:
if pos=='':
pass
else:
pos=int(pos)
except:
print pos
print("exititng...")
exit()
if cur_pos==pos or pos=='':
#suggestion from @Todd W to sleep before next read
sleep(0.3)
pass
else:
print("Current pos: {0:d}, New pos: {1:d}".format(cur_pos,pos))
print("Updating...")
with open("output.txt","w") as f:
f.write("0")
#do some computation with the data
sleep(2)
cur_pos=pos
print("Current pos: {0:d}".format(cur_pos))
with open("output.txt","w") as f:
f.write("1")
pass_action.py
The action passer will accept a command line argument, write it to input.txt, then wait for output.txt to read '1', after which it will print done and exit.
import sys
from time import sleep
newpos=sys.argv[1]
with open("input.txt","w") as f:
f.write(newpos)
while True:
sleep(0.1)
with open("output.txt","r") as f:
if f.readline()=='1':
break
sys.stdout.write("done")
