Experimental Physics and
Industrial Control System

"Stevens, James" <[email protected]> · Fri, 20 Feb 2015 17:12:04 +0000

Kay,

The PLC5 ladder logic executes the data transfer to 
the ControlLogix PLC. 

I worked on the Epics interface to the ControlLogix PLC,
while Rick Putnam, a talented mechanical engineer here 
at APS, wrote the PLC5 ladder logic.

I am working on a technical paper that describes how we
developed & implemented the PLC5 & ControlLogix network
system.

This is a description of Rick's PLC5 ladder logic..

"Data sent to the central ControlLogix PLC (CLX) is assembled in a PLC 5/20 in several files, depending on the data type (i.e. integer, floating point (real) and string). The data is sent from the PLC 5/20 to the CLX using three discrete read/write message instructions, one for each data type, written in the PLC5 ladder logic. The PLC5 ladder logic executes a “PLC5 typed write” command using a multi-hop mode message function."

"The PLC5 data is received by the ControlLogix PLC and inserted into file of correct type that has been mapped as a PLC5 message. Data from these files is moved into files that are read by EPICS. Data can also be transmitted to the PLC5 from the CLX processor by using a “PLC5 typed read” message in much the same manner as above."

I hope this answers your question.

Regards--Jim Stevens
________________________________________
From: Kasemir, Kay [[email protected]]
Sent: Friday, February 20, 2015 8:19 AM
To: Stevens, James
Subject: Re: Looking for Allen Bradley PLC5 Ethernet support

Hi Jim:

Interesting!

After plugging all the network cables in, what else is required to get the data from the PLC5 onto the ControlLogix PLC?

Is there a certain magic mode that mirrors all the PLC5 data on the ControlLogix PLC without much ado?
Or do you add logic to the ControlLogix PLC to periodically 'fetch' data from the PLC5, while the PLC5 code otherwise stays the same?
Or do you need to add logic to both the PLC5 to 'publish' the data, and the Control Logix PLC to 'receive' it?
.. just once for all the data, or once for every piece of data that you want to transfer?

Thanks,
Kay

> We read Allen-Bradley PLC5's that monitor the water system
> over the network using an Allen-Bradley 1785-ENET Ethernet
> module.
>
> Each PLC5 transfers data to an Allen-Bradley ControlLogix PLC.
> The ControlLogix PLC is read using the Epics EtherNet/IP driver.
>
> http://ics-web.sns.ornl.gov/kasemir/etherip/
>
> This scheme was developed to save the cost of replacing
> our installed base of Allen-Bradley PLC5's.  It  was cheaper
> to buy a 1785-ENET module for every PLC5, and a single
> Allen-Bradley ControlLogix PLC.
>
> Regards--Jim Stevens

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System