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Help Modbus communication [message #1794971]

Tue, 11 September 2018 21:24

Rodrigo Esposito

Messages: 24
Registered: August 2016

Junior Member

Hi, I'm developing an application for the control of a small test plant.
the data is acquired by sensors in raspberry and sent via modbus tcp / ip to the client (Modbus master) running on my pc (FORTE). The connection between devices has already been made.
I'm having trouble performing the data read on 4DIAC. I'm using the client block to make the requisitions. The attached figures show my IDE.
Why can not I get any value in the RD_1 field?

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[Updated on: Wed, 12 September 2018 17:16]

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Re: Help Modbus communication [message #1795017 is a reply to message #1794971]

Wed, 12 September 2018 19:20

Alois Zoitl

Messages: 1585
Registered: January 2014

Senior Member

Hi,
the problem is that you haven't connected anything to the SD_1 and RD_1. However these are in the defintion of the Client fb of type ANY. In order to correctly recieve or send data you need to typify it. The easist way is to connect them to other functionblcoks with the type you want to send or receive.

I hope this helps.
Alois

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Re: Help Modbus communication [message #1795050 is a reply to message #1795017]

Thu, 13 September 2018 14:47

Rodrigo Esposito

Messages: 24
Registered: August 2016

Junior Member

Thank you, once again, for you attention. I just figure how to manage it e now everything is working correctly!

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Re: Help Modbus communication [message #1795052 is a reply to message #1795050]

Thu, 13 September 2018 15:11

Alois Zoitl

Messages: 1585
Registered: January 2014

Senior Member

great!

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Re: Help Modbus communication [message #1850387 is a reply to message #1795050]

Mon, 28 February 2022 21:13

Emmanuel Luwaca

Messages: 4
Registered: February 2022

Junior Member

Hi Sir

Would you be so kind as to send me an example on how you managed to read the data using modbus. I'm trying to read UINT from a holding register.

regards

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