Error: Modbus exception 254 on modbus-tcp

General
1

Hello all, i have gateway to read data from modbus device and i use modbus-tcp in node-red to read data form device.
I config listener port 505 in gateway ,when i read modbus it response "Error: Modbus exception 254".
Could you please help me in this regards?

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This above image is the setting of gateway.
But when i use modbus-serial (USB-modbus) as the same address, it succes to read data.
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Flow

[{"id":"62059c78.4b0de4","type":"modbus-read","z":"7121fe96.cef1e","name":"","topic":"","showStatusActivities":true,"logIOActivities":false,"showErrors":true,"unitid":"1","dataType":"HoldingRegister","adr":"1","quantity":"10","rate":"10","rateUnit":"s","delayOnStart":false,"startDelayTime":"1","server":"20de53c2.01385c","useIOFile":false,"ioFile":"","useIOForPayload":false,"x":170,"y":300,"wires":[["d6c37260.6d189"],[""]]},{"id":"20de53c2.01385c","type":"modbus-client","z":"","name":"","clienttype":"tcp","bufferCommands":true,"stateLogEnabled":true,"tcpHost":"172.20.10.4","tcpPort":"505","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","unit_id":"1","commandDelay":"1","clientTimeout":"5000","reconnectOnTimeout":true,"reconnectTimeout":"2000","parallelUnitIdsAllowed":true}]

2

hi,
the port to use by default with modbus tcp / ip is 502, not 505, try it.

3

using a serial connection would probably require a so called null-modem cable, where RX/TX lines need to be reversed on one side.of the connection.
Edit: Ah, my bad...thought from the pics that you were trying to read via serial.

4

i change listener port to 502, but it's not working.

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5

...try the TCP-Type from DEFAULT to RTU-BUFFERED in the client settings

7

it's not working.
i think the problem was my gateway, i'll find another gateway and try again.

8

ok but if you need help put some more data because without information it is difficult to give you support...

9

Thank you.

10

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