Wiring Micrologix 1100

[Yertoo]

I have a MicroLogix 1100 and it's capable of ac or dc output voltages. What I don't know is how I'm supposed to tell the 1100 to use dc for the output. I tried going to i/o configuration but I don't see anything about output configurations anywhere, just input latching and filtering. I am using Rslogix Micro Starter Lite, if that helps with your answer. Thanks for any help!

 

[KuulKuum]

It always helps to post the actual PLC model/part number when requesting help.

Most models of the ML1100 the outputs are "Relay" outputs, which means you can use AC or DC voltages or possibly even a combination of voltages sources depending on PLC model.

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1763-um001_-en-p.pdf

 

[Yertoo]

It's an Allen Bradley 1763-L16BWA/B MicroLogix 1100. You're right, they are relay outputs and they definitely can use ac or dc, but what I mean is how do I tell the 1100 that I want to use dc?

 

[KuulKuum]

You don't need to...
The PLC will "energize" the internal relay and your discrete output contact operates the connected device (AC or DC)

 

[Yertoo]

That's what I needed to know, thanks.

 

[I_Automation]

It's an Allen Bradley 1763-L16BWA/B MicroLogix 1100

That model is all relay outputs.


Watch other models that can have a mix of relay and DC only transistor outputs.


Look at the COM terminals and it will say VAC/VDC or just VDC.

 

[Yertoo]

Yeah mine has vac/vdc next to every output. I just wired output 0/1 to a pressure transmitter, but it's not turning on. That's why I was asking how I am supposed to tell the 1100 to use dc output. Kuulkuum says I don't have to tell it. I don't have a volt meter with me I can't check to see what I'm getting from the output.

Here is two links to pictures of my 1100 and the connection to the transmitter, maybe that'll help someone help me lol.
https://imgur.com/D9uzlA8
https://imgur.com/spFMT6p

 

[I_Automation]

You would wire +DC to COM for output 0/1, then output 0/1 to the pressure transmitter brown wire and DC Common to the pressure transmitter blue wire.


If this is a used ML1100 there's a good chance the relay contacts are burnt, try jumping across the output from COM and see if it powers up, if it does move to an unused output and change the program for it.


If it doesn't power up there may be a power problem with the 24VDC or the transmitter itself. Also you could have the DC reversed.



Without a meter you can hook some leads on a 24V light and use it to test for 24V

 

[mylespetro]

First of all, why are you trying to wire a pressure transmitter to a digital output? Second of all, if for some reason you would want the PLC to turn the transmitter on/off with the output, you would need to take +24VDC from a DC power supply, wire that to the VAC/VDC of the output, wire from the 0/1 to the + terminal on the transmitter, and then the - of the transmitter back to the -VDC terminal on the power supply. Right now, it looks like you've got a "dry" (unpowered) contact wired across the +/- power terminals on the transmitter, with no power anywhere in the loop.

 

[I_Automation]

Yeah mine has vac/vdc next to every output. I just wired output 0/1 to a pressure transmitter, but it's not turning on. That's why I was asking how I am supposed to tell the 1100 to use dc output. Kuulkuum says I don't have to tell it. I don't have a volt meter with me I can't check to see what I'm getting from the output.

Here is two links to pictures of my 1100 and the connection to the transmitter, maybe that'll help someone help me lol.
https://imgur.com/D9uzlA8
https://imgur.com/spFMT6p

I just looked at your pictures better.


The black wire to the pressure transmitter is NOT connected to the VDC COM terminal.


The outputs do not provide 24V.


You have to run the black wire to the -DC terminal of a 24V power supply and another wire from the +DC of the power supply to the VDC COM terminal, then the PLC will control the 24V to the pressure transmitter.
EDIT: Never a good idea to use the 24VDC supplied by the PLC to any field device, or try to power anything other than indicator lights off of it. Best to use a 24V power supply as then any problem would shut down the 24V power supply but not kill the PLC.

 

[Mickey]

First of all, why are you trying to wire a pressure transmitter to a digital output?

To the OP, please respond to this (above quote). From the picture the pressure transmitter appears to be a loop power transmitter. (would have to see the complete catalog number of it to be sure). That wiring is completely wrong for a pressure transmitter.

 

[I_Automation]

To the OP, please respond to this (above quote). From the picture the pressure transmitter appears to be a loop power transmitter. (would have to see the complete catalog number of it to be sure). That wiring is completely wrong for a pressure transmitter.

I didn't realize (look close at the terminals) that was a 2 wire transmitter. I was presuming the third terminal was the analog output, not a test input.


Here is how that would be controlled by a PLC, but you will need a 4-20mA analog input card.

 

[Mickey]

I didn't realize (look close at the terminals) that was a 2 wire transmitter. I was presuming the third terminal was the analog output, not a test input.


Here is how that would be controlled by a PLC, but you will need a 4-20mA analog input card.

Yes,and as mylespetro ask. Why would someone do that?

 

[I_Automation]

Yes,and as mylespetro ask. Why would someone do that?

I'm guessing, since his photos are on a desk, it's something he had sitting around to begin programming PLC's


I don't believe anyone would ever do this in a real world application (Clarification: anyone with over 5 years PLC experience)


I was going to add an edit, but just missed the 60 minutes, that if this was done then he should wait until the signal from the transmitter stabilizes after powering up the output, and that could take a second or 2.