Trouble using a DirectLogic 05 as a Modbus RTU slave

[theColonel26]

I'm trying to use a DirectLogic 05 as a Modbus RTU slave and control it over RS-232 using a .Net Program. I am using the nmodbus4 library.

The trouble is I can't get them to communicate. When ever I send it a command the serial port just times out. I tried this using Python and the minimalmodbus library with the same result.

Is there something I need to configure out the PLC to allow it to be used as a slave? the modbus is already enabled on the port. I can't find anything else that I need to configure in the manual.

 

[OpZed]

Use a standardized tool first, like Modbus Poll
http://www.modbustools.com/modbus_poll.asp

Prove the hardware and settings first, after you get that working then you can start your development with some confidence that it should work correctly.

 

[theColonel26]

Thanks I did, and it seems to definitely be an issue with the PLC. Still haven't figured it out yet but at least I know it's not my code.

 

[jgreenewv]

Which port are you attempting to connect to? Have you verified the port settings using DirectSoft?

 

[icky812]

As a FYI this thread is also being explored over on the AutomationDirect forums.

 

[theColonel26]

I figured it out. I was using parity none instead of parity odd.

also those DL 05 have to have a program written to them with a END block in it. Other wise they don't cycle, they just sit there.

ETA:

Yup yup I posted the solution over there too.