Problems with ModbusRTU slave telegrams


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I am trying to acquiring data from a ModbusRTU Slave. But I have got some problems with the configuration of the appropriate device or the channel.  

I always receive 2 answers. None of them doesn't contain the information. 

Tx (17:13:03.000): \001\003\000\034\000\002\100\001
Rx (17:13:03.002): \001\003\000\034\000\002\100\001\001\003
Rx (17:13:03.009): \004\000\000\000\000\250\051
Tx (17:13:04.000): \001\003\000\034\000\002\100\001
Rx (17:13:04.001): \001\003\000\034\000\002\100\001\001
Rx (17:13:04.008): \003\004\000\000\000\000\250\051

As you can see in the screenshot - in the Command/Alert window I always receive the "CRC Fail"-Message.

The Baudrate, Com-Port, and so on are configured correctly. 

Could you help me to solve the issue or say me what I am doing wrong? 

Thank you in advance.  


Best regards



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You are getting an echo back of the transmission.  You are seeing what DAQFactory is transmitting echoed back, then the proper response from the device.  DAQFactory only expects the device response, but since the transmission and response format are very similar it can't tell the difference and misinterprets it, throwing the error.  The echo is probably a setting in your RS485 port (or 232 I suppose, but more rare), or in the Modbus Slave device itself.  

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