PLC to PLC Ethernet

Dani610 · May 20, 2018

Hello Everyone,

I am using two AB ML 1400 that are connected via ethernet switch. Input is given at one plc and output is on the second plc. Now I want that whenever the ethernet cable of first plc is unplugged the output should turn off. what should I do. what is the appropriate approach.

Thank you

Dani610 · May 20, 2018

Dani610 said:
Hello Everyone,

I am using two AB ML 1400 that are connected via ethernet switch. Input is given at one plc and output is on the second plc. Now I want that whenever the ethernet cable of first plc is unplugged the output should turn off. what should I do. what is the appropriate approach.

Thank you

I am using Rslogix 500 in Vmware workstation 14 player

James Mcquade · May 20, 2018

I am a little confused.

when the Ethernet cable is unplugged, you want the outputs of the first plc to die or the second?

if its the second, I would set up a heartbeat signal between the two plc's.

maybe some can answer as to how, I am not that good at it.

james

Dani610 · May 20, 2018

James Mcquade said:
I am a little confused.

when the Ethernet cable is unplugged, you want the outputs of the first plc to die or the second?

if its the second, I would set up a heartbeat signal between the two plc's.

maybe some can answer as to how, I am not that good at it.

james

I want the output on second plc to die

alan_505 · May 21, 2018

Maybe you could monitor the message error bit if you are doing a read in PLC2 from PLC1.

Alan

Dani610 · May 21, 2018

alan_505 said:
Maybe you could monitor the message error bit if you are doing a read in PLC2 from PLC1.

Alan

Yes i am doing that i have stored the input in an integer bit and then reading that integer bit in PLC2. it reads the data fine but when i unplug the ethernet cable nothng happens

alan_505 · May 21, 2018

If you are doing a read message in PLC2 of an integer in PLC1 then when the message tries to do a read and the ethernet is disconnected the message should show an error, MG9:0.ER.
MG9 = message file.

Alan

This wont work if you are doing a Write message from PLC1 to PLC2.

Dani610 · May 21, 2018

below are the codes. i am reading the integer N:20 in PLC2 and storing that in N23:0 then using that to fire output but when i unplug the ethernet cable of PLC1. the PLC2 logic remains the same nothing happens output stays on

Dani610 · May 21, 2018

alan_505 said:
If you are doing a read message in PLC2 of an integer in PLC1 then when the message tries to do a read and the ethernet is disconnected the message should show an error, MG9:0.ER.
MG9 = message file.

Alan

This wont work if you are doing a Write message from PLC1 to PLC2.

and this is the setup screen of read msg

alan_505 · May 21, 2018

I cannot read those images they are too blurry, I see you are using a message instruction, instead of a full screenshot just do the message instruction and the message instruction dialog box.

Alan.

Dani610 · May 21, 2018

alan_505 said:
I cannot read those images they are too blurry, I see you are using a message instruction, instead of a full screenshot just do the message instruction and the message instruction dialog box.

Alan.

Here they are

Dani610 · May 21, 2018

thank you all for your feedback i have found a solution now the only problem is that it doesn't start receiving msg when i plug the ethernet cable in again. below is the output logic on plc 2. the enable bit and error bit stays on

If i i don't use the .ER bit in parallel with .EN bit in rung 0 then the .ER bit in rung doesn't work.

PLC to PLC Ethernet

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