Did anyone use Allen Bradley Flex IO encoder module?


Thread Starter

Dobrowolski, Jacek

Hi everybody,
I'm trying to configure DeviceNet network. Whole stuff is from Allen Bradley. I can't configure Flex encoder module 1794-ID2/B. RSNetWorx can't recognize it. Scanner 1747-SDN reports wrong I/O size. Any solutions or similar experiences ?

Jacek Dobrowolski
Haven't used the encoder, but I have been playing with devicenet some lately. The most important part is to make absolutely certain that you have the correct EDS file for the device. Note that this may not be the most current. Check your revision number to make sure you have the right version.


Hi All

Just a word of warning to those using AB products and DeviceNet.
We are configuring quite a medium sized system using SLCs and Point I/O products. Since the point I/O product is new to us we were test benching 40 units to see what they could do. We found out more than we bargained for. When we implemented the ADR "feature" the point I/O started to pulsate sporadically with the LEDs
flaring up, etc almost as though someone was over supplying the voltage.

The end result was a blown SDN scanner, another scanner suspect and 5 point I/O modules blown (with the current shortage of this product that creates another problem, has anyone got a supply available?). Of greatest concern was the erractic nature of which the ACTUAL I/O points were operating, totally out of control - imagine if we were connectted to live equipment when this feature was turned on.

AB were quick to react to the problem by advising that we should not use the ADR feature and that they had heard that simliar instances had occurred on VSDs and even ControlNet.

Has anyone got more info on this problem? Has anyone else had this problem? Was anyone who purchased point I/O informed by AB of the potential problem or am I again the lucky first ("sir, that is the first time we have heard of that").

Naturally we have documented this for AB and even produced a video of the event which has been forwarded to AB by email, just so they can witness first hand what we experienced.

Allan Dow

Embedded Systems & Solutions

Kevin MacMillan

Go into your RSLogix program and access your I/O configuration file by simply clicking twice.

Now click on your 1747-SDN module, twice.

Now you will need to set your scanned Input and output words.

When you program your SLC system you use the G file to configure the specialty module's I/O image file. This configuration data is based on the devices that you have on the RIO link. G file configuration consists of setting logical device starting addresses and the logical device image size of each physical device with which the specialty module communicates.

Neither your application program nor your programming device can access or alter the G file during SLC operation. To change the G file you must go offline, make any necessary changes, and download the altered configuration.

RSLogix 500 - Copyright Rockwell Software 1999

Do this wrong and you can also make a nice set of flashing leds.

Good luck.