AB- PLC Hardwiring Interface using Din Rail IFMs


Thread Starter


Has anyone used the Interface modules from AB or Weidmuller that go with PLC5 or SLC 500? I am looking for some help in this area, the selection is complex and I am not sure if its a good idea..any thoughts?

Are there any other vendors making these IFMs?
What about the prewired cables are they useful? How much do you think it will add to my cost if i used IFMs instead of Din Rail Terminal Blocks?

thanks for your time

List Manager

Cost wise it is probably a break even thing, maybe even slightly to your favor considering labor to wire the terminals. However, let me tell you about my one and only experience with them.

A project I worked on used them for all I/O as a cost savings device. During startup, we experienced MANY wierd glitches. After spending a lot of time looking for the glitches, we finally determined that the connectors on the
terminal strip modules would vibrate and come loose (sometimes intermittantly). It seemed to be a quality control problem because some never did it and others did it on a regular basis. We finally ended up gluing the connectors into the terminal strip modules on the ones we had
problems with. I would guess we glued perhaps 10% of them.

Personally, I do not like them and consider them to be rather flimsy and do not use them, and would not unless forced to do so for some reason. I also find them harder to put a meter on for testing, plus the terminal strip module itself takes up more space then the equiv number of IEC terminals, and you will need some terminals for commons anyway. I see no real benefit to them when you can get flex I/O modules that have all the terminals built in and take up far les real estate.

Bob Peterson
I used these modules extensively with Honeywell PlantScape equipment (the 1492 model IFM's and cables). They were a good choice for what I was doing because space was not an issue on any of the projects and they made wiring much easier (if you ever try to get the AB modules wired and then troubleshoot you will understand, it is impossible).

The cables are a must. They aren't that expensive (well..., a few hundred bucks each), but will save hours of wiring and fixing the errors. NOTE: Watch out for errors in the cables also, we got a batch of 16pt AI cables that were missing a jumper.

Good Luck and I hope I helped, feel free to E-Mail with any questions.

[email protected]

Jocko Harmet

Many vendors including Allen bradley make IFM's, the reason for using them is to reduce panel assembly labor and reduce the overall dimensions of the panel. For High density IO, they are sometimes the only choice, as the module will simply have a DB25 or similar connector. So for cost comparison, you need to look at your assembly cost and how using IFM's and the associated hi density io modules will affect the size of your panel.

Jocko Harmet
Phoenix, AZ
In various systems with SLC's, we've used the IFM's from AB, as well as similar modules from Entrelec and Phoenix Contact. Generally we can use them more often for input cards than output cards, because often our outputs require interposing relays with different current requirements and so are wired individually. Our experience has been that the overall cost is quite similar once the labor cost is included, but in a large panel using IFM's can get it out the door a day or two sooner.

Don Zunti
Delco Automation Canada