1771-IFE Series?

Can anyone tell me if any series of a 1771-IFE card higher than Series A can accept different inputs e.g. channels 1-8 single-ended and channels 9-16 differential?

IF this is not allowable, then I have a question following a bit of system info for your perusal:

We currently have a PLC5/40 with a remote rack which has an in-use 1771-IFE. Only the first 8 channels are being utilized. All 16 channels have been configured for single-ended 4-20mA inputs with corresponding BTW/BTR data files. The 8 existing field devices are provided looped power from a 24vdc source in the PLC cabinet and the returns of course are terminated on channels 1-8 of our IFE.

Now...I need to add two more field devices which happen to be also 4-20 outputs, however, these two are self-sourced e.g. the positive/negative leads are available to terminate at the PLC analog input.

And the question: Can anyone say what would be the best way to connect these two inputs to channels 9 and 10 on the IFE?

Your help and time is very much appreciated.

Easiest solution would be to install signal isolators, I usually use the SIX model from Moore Industries,
here's a link: http://www.miinet.com/products/sg_signal.shtml

They have a new multiple channel model the MIX that would take up less panel space.

Thank you, Ken, for your reply. So I take it that I could not simply apply the +- 4to20 to the 1771-IFE input channel 9 e.g.? This field device of which I speak is a belt scale by Milltronics. It outputs 4-20mA non-isolated. However, in the controller there is an optional Milltronics Sil-1 Isolator module (currently not hooked up) 4-20 input, 4-20 isolated output. This sounds similar to the one you suggest. The existing 8 analog input channels on my IFE source 24vdc out on each channel + terminal and the 4-20 device output returns the opposite terminal. Any further thoughts? Thanks.

You ever take one apart? There's jumpers!

The power doesn't come from the module; you have to supply your own. Wire it up per your need. Here's the module info for series C. Should be the same for A and B.

Manual --> http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1771-in045_-en-p.pdf

Use the signal isolator provided in the equipment.

As tomalbright points out, the IFE module doesn't source power at all. The channel input takes a current in across an internal resistor (250 Ohm) to module common.

The basic issue here is: If all your transmitters can tolerate the (-) tied together at the module common on the IFE card. With isolated outputs on the transmitters, this is not a problem.

Thanks, Mellis and Tom, understood. All card channel jumpers are configured for 4-20 current single-ended. I will use the isolation interface to avoid the issues you guys have pointed out. I do appreciate your information. If there is a place to give you a vote I will do so. Best regards.

Tom/Mellis:

If you don't mind I do have one last curious question that you probably have some insight.
Have either of you seen where the inputs on the IFE-A card (wired and configured for single-end current) do not use the common on each group of 4 channels and the negative of the power supply is only connected to the bottom common on the card rail? The power supply +24vdc is looped on a T strip to all the 2-wire transmitters and, of course, the returns are terminated on each channel.
This system has been working for quite some time without issues, but I don't know I have seen such an arrangement. If you can give me some insight I would appreciate it.
thanks again.

See PDF below, pay special attention to note 1.
"All commons are electrically tied together inside the module."

Thank you, Mickey, for the response. You are correct. Albeit, the A/B configuration/wiring layouts show the supply returned to the commons on the rail. No difference I suppose. Just helps keep my half mind on track.

I am not sure what is wrong with the pdf file you sent. I locked up my puter and slowed the network down to a crawl. Maybe the file is okay and it is just too early in the morning for the computer.

At any rate, thanks again. Best to you.

I vaguely remember that module, and trying to fit all the negatives on that last terminal. It's bad enough with 4 wires! The jumper arrangement I have seen in many and various ways, at the module, or at a terminal strip.

Here is a picture