M172 - Modbus Master

[geoffrey_tegny_]

Hello guys,

I have some troubles to set up the a TM172PDG42R as Modbus master.

- I set the RS485-2 to Modbus master and the different modbus properties,

- I created a "Generic Modbus" device properly and set its "Modbus address" and "Node number" to 2,

- I added a "FC 03 - Read Holding Register" with a "start address" to 2 and assign the object to a variable created in PLC "Status Variable"

But not chance.. The xx flag shows a timeout (at starting) error and I actually cannot see any request message from the PLC with a modbus sniffer.

Is there any TVDA available on how to set up a Modicon M172 as Modbus master properly?

Is my RS485-2 com dead?

Thank you in advance!

[Rodrigo_Garcia]

@AmeliaFaraci 

Hello Amelia,

Could you take a look to this post?

Regards,

Rodrigo.-

[Anonymous user · Accepted solution]

Hi Geoffrey,

to verify whether the RS485-2 is still alive, suggestion is to download an empty project on the PLC (by Download All) and afterwards try to connect to the RS485 port via EcoStruxure Machine Expert HVAC Installer or via Modscan.

Please let us know, so that we can eventually follow-up with your enquiry.

Have a good day,

Pierpaolo

------

Pierpaolo Armeli

Technical Expert Community Facilitator & HVAC Expert

[ismailozinan]

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[geoffrey_tegny_]

Hello Pierpaolo,

Thanks for your help.

I actually "fixed" my issue by sending the code again and again to my controller.. I had to set up 19 controllers and had to send again when the communication were not working properly. I don't know if I were no patient enough or send it again fixed the problem.

But now everything is fine.

Thank you!

[geoffrey_tegny_]

Good tips.

thanks "ismailozinan"

[Anonymous user]

I am using M172PDG42R and have an issue with RS 485 communication. I have done all possible requirement for which I should get Data from PLC through RS 485 (2) port. I am not able to get value in modscan software. Please guide. 

[Anonymous user]

Please guide me . I am facing issue for Modbus communication of M172 PDG42R RS485

[Bastian_Schmitz]

Did you have problems to read values or to write values or booth in the case the TM172P is the modbus master? Please check the serial line parameters which you configure via configuration. These parameters will be used after a download all via CONNEC.PAR. The parameters which you can enter via BIOS Parameter or Commisioning will be over writter from the configuration of Modbus Master in configuration. Did you check the status of your slave like explained in the former posts?

[ismailozinan]

Hello,

if you are using modbus scan software.Modbus scan software is master. In this case TM172 should be as a slave

Please check step by step at  below lines. After that you can not take a response from TM172, could you plase connect to TM172 via micro USB cable or ethernet for check modbus parameters of RS485-2 via commisioning tab.

BR

[Bastian_Schmitz]

As additional information. If you use RS485-2 as slave a change of communicaiton paramters (Baudrate;Parity...) need all time a restart of the controller. To restart the controller remove the power supply and the Mini USB cable. Did you get a response or a error code from modscan?