Today is...
Tuesday, August 21, 2018
Welcome to the Modbus Community, about
the world's leading automation protocol.
Leuze MSI430 Safety PLC
Writing to registers of a MSI430 safety PLC from Leuze Electronic using a HMI as a master via Modbus TCP

Hi all,

My Task: To control write to registers to my MSI430 safety PLC from Leuze Electronic using a HMI as a master.
Protocol: Modbus TCP

MSI430 (Modbus TCP - server/slave)

Generic HMI (Modbus TCP - client/master)

I'm reading Okay from the Register address 401101-40110.
But I'm not able to write to the MSI PLC to address 402101-402109.

Please see the attached images for gateway description for the device.

Please advice/guide on how this could be done.

I have tried using MBPoll and it says Illegal Data Address. Please find the below link for the gateway manual document

Any help/advice greatly appreciated

By W.L. Mostia on 16 March, 2018 - 11:53 am

I don't know anything about this PLC gateway, but you might look at Table 6.8 (page 57) in your manual, which I think indicates you can only write 5 words at a time for Dataset #1. Your write addresses are 2101 to 2109, which is 9 words. Are you trying to write too many words at a time thus getting an illegal address message due to your upper address?

William (Bill) L. Mostia, Jr. PE
ISA Fellow, FS Eng. (TUV Rheinland)
WLM Engineering Co.