I/O Messaging (Class 1, Producer/Consumer) between PLC and PC?

[LGreen 0]

I currently use custom PC-based control software that retrieves data from PLCs using explicit messaging, but I'd like to convert this to implicit messaging, to take advantage the fast data exchange. PLC programming isn't my strong suit, so I've started by getting two ControlLogix PLCs exchanging information via implicit messaging (producer/consumer) -- I was hoping to find enough information to extend this to a PC communicating with the PLC, but so far haven't had any luck. Is it even possible to configure PC based software to exchange implicit messages with a PLC? At an RPI of 2ms? Thanks in advance!

[Ken Roach 194]

Most HMI programs stick with explicit messaging, but it's definitely possible to run an I/O connection to a PC. SoftLogix 5800 never caught on the way ControlLogix has, but it could handle more data faster than any slot-based controller over EtherNet/IP. My principal recommendation is the EtherNet/IP Adapter stack from Real Time Automation. Of all the EtherNet/IP driver projects I've seen, most of the successful ones started with RTA. There's also an open-source adapter project if you have an appetite for that sort of thing; it's called OpENer and is on GitHub.

[pmdavis300 0]

Wouldn't an OPC server take care of this?

[Ken Roach 194]

I've never been able to push an OPC server reliably faster than 50 to 100 milliseconds update rate. For real cyclic I/O, you need a real Type 1 connection.