Pepperl+Fuchs Blog

New Add-on Instructions for AS-Interface Gateways

Posted by Tim Cicerchi on Fri, Jul 20, 2012

Using RSLogix 5000 software from Rockwell Automation

Allen-Bradley is one of the most popular PLC makers in the United States.  And I think manufacturers love them because the software is user friendly and the instructions are well described and easy to understand.  Even a novice programmer can get up to speed without memorizing a bunch of commands.  There's no need to put special characters like K, or d, or M in front of numbers, and no need to remember what type of bracket has to be used with this instruction.

Pepperl+Fuchs has no vested interest in promoting Allen-Bradley products, but rather promotes hardware that connects to Allen-Bradley PLCs.  So over the years, we have had to become experts in the RSLogix programming software.  I've found that if I can’t tell my customers how to interface my hardware with their PLC they don’t want to buy.  And that makes sense.

Beginning with RSLogix 5000 V16, Rockwell Automation included add-on instructions that greatly simplify programming and configuration.  Normally instructions like COPY, MOVE, ADD, etc. are already created for you. But what if you could make your own?  That is exactly what they now allow you to do. These instructions perform a very complex set of operations in one single rung of ladder logic.

Of course there are some limitations—I found that you can’t use pointers to I/O as an input/output parameter; you have to pass an entire array to the add-on instruction instead.  But once you figure out the limitations and the tricks, the programming becomes easy.  

You don’t need to use these instructions, of course.  You could spend your time writing and rewriting your own ladder logic to interface with all the functions of our AS-Interface gateway or RFID systems.  You could spend hours on the phone with me while I wade through a thousand rungs of ladder logic, spread out over 30 routines, trying to debug your code—and what a daunting task it can be to debug someone else's code. Or you could take advantage of the new add-on instruction we created for our RFID systems, AS-Interface gateways, encoders, etc. With it, you only need to program it once and there is no limit to the kinds of devices you can incorporate into these instructions.

These add-on instructions save my customers time because they don’t have to write the code, and they save me time because I don’t have to debug it.  And if I do need to help my customers with the programming, then it is much easier for me because I wrote the code.

Take a look at this video where I use my add-on instructions to interface with our AS-Interface gateways:

The above video is actually #5 in a series of 'How to' AS-Interface programming videos. Here are the other videos for you to review, starting with the first one:

  1. How to Build an AS-Interface Network
  2. How to Set Up AS-Interface EtherNet/IP Gateway in an Allen-Bradley PLC
  3. How to Set Up an AS-Interface EtherNet/IP Gateway in an Allen-Bradley PLC w/ EDS File
  4. How to Set the IP Address of an AS-Interface, EtherNet/IP Gateway

Topics: Troubleshooting, AS-Interface, Software

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