Contact without a coil

Mat.Hinse

Member
Join Date
May 2016
Location
Ottawa
Posts
7
Hi, I am trying to transfer a PLC program from a FX2N to a FX1N and to do so I have to change some contacts in the program that are in the range of over 1500 for the auxiliary relays M (since it's outside the range for the FX1N and I couldn't write it to the PLC).

The problem is that they are all contacts that I cannot find the coils for. I am not sure if they are the input of the sensors or if the program will be still be able to function correctly if I replace the PLC even if it's not the same contact number since they don't have a coil?

Is it possible that the HMI attached to the PLC receives the signal from the sensors and then sends them to the PLC giving the contacts numbers that I have change?
 
Difficult to say...


If they are not listed in you program they could just be push buttons etc coming from the HMI – or system bits (M8000 etc), or just code that’s unused and just been left behind. I take it they are not Labelled?


If they are from the HMI and you change the contacts in the PLC you will need to also change them in the HMI.

What HMI is it? And do you have the HMI project?
 
It's more likely that the inputs have been buffered inside the plc. Check to see if the inputs (X) words are being written into M words. I have seen this done on other FX series plc installations.
 
It's more likely that the inputs have been buffered inside the plc. Check to see if the inputs (X) words are being written into M words. I have seen this done on other FX series plc installations.

Don’t know why I didn’t think of that as I actually do it myself (for simulation purposes).
 
You need to get the hmi program and use the cross reference function.
This will tell you immediately if the contacts are being used from there.
As an aside, putting a plc program from a bigger model into a smaller one is never the right thing unless you know for sure the program doesn't use any of the higher functions.
 
Thank you all for the responses,

Twocozz, there are some M8000+ but the one I had to change were in the range of the M2000 which is just auxiliary relays in the FX2N. But like you said it might be from the HMI. I'm new to plcs and I haven't been familiarised on HMIs yet. I also do not currently own the program to work with HMI (GX works3 I think?). I don't know what HMI it is yet but I have someone that's going to supply that to me.

Soggy Canuk, I don't know what you mean when you say that the inputs might have been buffered? But there are in the program some input in X.

Shooter, I agree but not sure how to find them. There are a lot of data registry change that I don't fully understand. Maybe it has to do with those?

Ronnie Sullivan, if I can get my hands on the HMI program I will try to do the cross reference function. Thank you for the aside, the thing is that I think that the FX2N is discontinued and we can't replace them.
 
Or you could just buy an Fx3U unit. Change the PLC type in your project to an FX3U and convert. The program should run without a problem (done this many times).

Of course the problem with this is that you would have to stump up for a new PLC.
 
Sorry for the delay in getting back to you. Things got crazy.

Most common way to load inputs (X) into internal registers (M) is with a move command.

[MOV X004 M6] This moves the value of X004 (0/1 value) into M6.

A more common format is as follows:

[MOV K4X004 K4M6] This moves the values of X004 - X020 into M6 - M22

This batch load saves programming rungs but makes following the transition a bit more difficult.
 

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