Loss Of Serial Link

[denise01]

Hi, I control five Altivar Inverers via Modbus using a CJ1M PLC with a SCU 31 Communication Card which uses Omrons Protocol Macro. Everything is controlled fine until two out of the five Inverters are stopped by Under Supply Voltage as in when an operator opens a guard. This causes the other three Inverters to show a SLF Fault which is loss of Serial Link. I can get round it by disabling the SLF Fault function but cant understand why the Serial Link is lost. As soon as I reset the two Inverters and the voltage is restored to them they are fine and Serial Link is restored. Is it to do with a voltage variance. My settings are 19200 Baud Rate and Bits 8, n. 1 as recommended in Protocol Macro. Any ideas would be appreciated. Regards Peter

[RDA]

Hi, test control cx protocoll if in case of error on a communication loop and active the jump to the next step or if you and stalling

[Jay Anthony]

How to Handle Missing Nodes in PMCR @ MrPLC.com

[denise01]

Many Thanks Jay, I take it that I have to add 5 steps in Protocol Macro because it is the first of the 5 Inverters that is affected when the guards are opened. I also take it that the Ladder programming is indication of the nodes being read correctly. Kind Regards Peter

[Jay Anthony]

The ladder shown will handle the missing node correctly.

[denise01]

Okay jay, Many thanks, still a lot to learn about mod us. Regards Peter

[denise01]

Sorry mod us!!

[denise01]

Hello Jay, I have tried to attatch the Protocol Macro that I uploaded from my SCU31 today but it wont allow me to. I have added five steps to allow for the first Inverter dropping out. But am not sure how to programme the Send and Recieve sections. I use port 1 on the SCU so I take it that I use 1 instead of the N2 shown in the PDF. Also instead of CR LF it is CRC16. Is there any way to send the Protocol file so you can see if I am on the right track. Regards Peter