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python - Raspberry Pi to AB controllogix: how to trigger output in GPIO based on continuosly reading plc tag value

问题描述

I've discovered pylogix on GitHub and have been playing around with reading/writing tags on an AB L71 CPU. I am successful at the read/write part, but what I want to do is trigger a GPIO pin output based on plc value being larger than 0.

I can't seem to figure out what I need to do to get the constantly updated value into the output function.

import threading
from pylogix.eip import PLC
from gpiozero import LED
from time import sleep

comm = PLC()
comm.IPAddress = '10.201.191.177'

def readdata():
    threading.Timer(1.0, readdata).start()
    x = comm.Read('parts')
    print (x)
readdata()

if x > 0:
relay = LED(2)

标签： pythonraspberry-pigpioplc

解决方案

很高兴看到我不是这个论坛上唯一对 PLC 感兴趣的人。我可能会为你推荐这个：

编辑：我阅读了您模块的文档。在文档下面尝试这个新代码可以找到https://gpiozero.readthedocs.io/en/stable/

import threading # I don't think this is necessity for your application
import time
from pylogix.eip import PLC
from gpiozero import LED
from time import sleep

with PLC() as comm #small edit here to control the closing of sockets upon exit
    comm.IPAddress = '10.201.191.177'
    running=True
    relay = LED(2) #I believe the previous version of your code was constantly overwriting your 'relay' variable with a new instance of class LED
    while running==True:
        x=comm.read('parts')
        if x > 0:
            relay.on()
        else: relay.off()
    time.sleep(.5)
#this will run forever updating your LED every 500ms, I would recommend writing code to exit this loop

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