PyConPro

PyConPro is a python library that allows us to make multiple consumer connections with multiple PLCs. At some point we would also like to add a feature allowing producer connections, but we don't know when that will happen.

This library has three main classes: Connection, PLC, and Consumer. Each of these are responsible for a different part of the Consumer/Producer protocol.

Usage Guide#

In order to start a connection with any PLC, an instance of the Connection class must be created and then started.

con = Connection()
con.Start()

Then, we can add a plc using the addPLC function.

myPlc = con.addPLC("172.16.13.200", slot=0)

To start a Consumer/Producer, we first need to define the ConsumerHint.

myHint = ConsumerHint(tag="test", datasize=6, rpi=1000, otrpi=1100)
  • Set tag to the name of the tag you would like to log.
  • Set datasize to the bytesize of the tag.
  • Set rpi to your desired delay between data points (in milliseconds).
  • Set otrpi to a number slightly higher than you rpi. (More documentation needed)
important

The datasize field must include an extra 2 bytes for the header.

I.e. if the tag has 4 bytes of data, set datasize to 6.

Common Issues

Before logging, make sure the tag is configured to accept a Consumer/Producer connection.

We also need to provide our consumer a function to handle the data we recieve.

def handler(bytedata):
print(bytedata)

Now, we initialize and start the consumer.

myConsumer = myPlc.addConsumer(myHint, handler)
myConsumer.Start()

You should get an output that looks something like this:

b'\x00\x00HB'
b'\x00\x00HB'
b'\x00\x00HB'
b'\x00\x00HB'
b'\x00\x00HB'
b'\x00\x00HB'
...

To stop the consumer, call myConsumer.Stop().

Full Example#

Here's a full example showing it's possible to log more than one tag at a time.

from pyconpro import Connection, ConsumerHint
from time import sleep
con = Connection()
myplc = con.addPLC("172.16.13.200")
def handler1(data):
print("My first consumer: ", data)
def handler2(data):
print("My second consumer: ", data)
con.Start()
myhint = ConsumerHint(tag="test", datasize=6, rpi=1000, otrpi=1100)
myconsumer = myplc.addConsumer(myhint, handler1)
myconsumer.Start()
sleep(0.3)
myhint2 = ConsumerHint(tag="test2", datasize=6, rpi=1000, otrpi=1100)
myconsumer2 = myplc.addConsumer(myhint2, handler2)
myconsumer2.Start()
con.Join()
con.Close()

The Please Reset Error#

If, after all consumers with a particular PLC are stopped, another consumer connection with that PLC is started, a PleaseResetError may be thrown. This could occur for two reasons:

  • The PLC stopped listening
  • An unhandled part of the Consumer/Producer protocol was used. This particular issue can happen if a consumer is started to soon after all of the other consumers for a particular PLC were stopped.

If either of these issues are encountered, just try to start the consumer again.

Note: this solution is abstracted away by the server.

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