What is the machine code for the M84-PLC1 and PLC2 devices?

What is the communication connection method used between these devices?

What specific error message is displayed on PLC2 when the connection is interrupted?

Is there any information available on the cause of the communication
The solution for the error described as "The communication connection between M84-PLC1 and PLC2 is interrupted" may involve checking the communication protocols, ensuring proper termination of the connection, checking the modems and communication cards,