Divers problemes avec NModbus4 library under CSharp with dot Net 4.8.1 when trying to create a Modbus Slave with Serial Port

[Martin Mayr]

Hello 

I encounter some strange difficulties with the NModbus4 Library under C# - hope somebody can help me here.

I try to implement a test Form within  C# with Windows FormsApp in .Net4.8.1 environment and when I try to create a ModbusRtuSlave 

with the command 

slave = ModbusSerialSlave.CreateRtu(1, serialPort);

I get an exception:

System.InvalidCastException: 'Impossible d'effectuer un cast d'un objet de type 'System.IO.Ports.SerialStream' en type 'Modbus.IO.IStreamResource'.'

In the documentation I found there would be a command allowing to use the SerialPort as second parameter , but when looking in the sources only the Modbus.IO.IStreamResource can be used, but I can't figure out how to create a IStreamResouce compatible from my SerialPort BaseStream ?

Anybody has an explanation or help for me please ?

Best regards

Martin

[PST]

Hi Martin

Help

https://github.com/sankarr/Nmodbus/blob/master/Modbus/Device/ModbusSerialSlave.cs

вторник, 15 апреля 2025 г. в 12:34:40 UTC+3, Martin Mayr:

[mm...@mmm-it.com]

Hello,

 

thanks for your response, unfortunately I still struggle with some details in my implementation, maybe you can help me once more:

 

I could connect the modbus now with your example but still don’t get the event rised for a Slave 1 Function 17 request … The Listen function is called in a parallel thread but I don’t get the

ModbusSlaveRequestReceived Event rised when my master sends the command. Since I have no access to the master sources (which are inside an application I didn’t make myself) I tried with polling and I see there is data coming from the master but I don’t get the Event from the ListenAsync() …. What could I have done wrong ?

 

In case I can send you my modbus slave test application project it’s a simple VS Studio application. Maybe you have another master to test with … ?

 

Maybe I just do something wrong with my Event Handler ?

 

Best regards and thanks a lot for your help.

 

 

    Martin

 

De : nmodbus...@googlegroups.com <nmodbus...@googlegroups.com> De la part de PST
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Objet : Re: Divers problemes avec NModbus4 library under CSharp with dot Net 4.8.1 when trying to create a Modbus Slave with Serial Port

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[ООО "ЦНТ-Энерго"]

Hi
function 17 ?
https://github.com/NModbus4/NModbus4/issues/132
==
testing function 03//06 ? ok

ср, 16 апр. 2025 г. в 10:44, <mm...@mmm-it.com>:

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[mm...@mmm-it.com]

Hello,

 

Function 17 should respond with the slave name  - but no event is raised for the  ModbusSlaveRequestReceived.

 

With Other functions I run into the same problem, no event is raised either …. Would you have a possibility to send me your private email ? I tried to send the project here but the zip files are refused to be attached ….

Maybe you can look in the sources if I do something fundamentally wrong ?

 

Best regards

 

Martin

 

 

 

De : nmodbus...@googlegroups.com <nmodbus...@googlegroups.com> De la part de ??? "???-??????"
Envoyé : mercredi, 16 avril 2025 11:38
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[mm...@mmm-it.com]

With function 3 – same reaction from the master who claims the slave failed to respond

 

 

    Martin M. Mayr

 

 

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De : nmodbus...@googlegroups.com <nmodbus...@googlegroups.com> De la part de mm...@mmm-it.com
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Objet : RE: Divers problemes avec NModbus4 library under CSharp with dot Net 4.8.1 when trying to create a Modbus Slave with Serial Port

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