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TOPIC: Modbus TCP

Modbus TCP 6 months 2 weeks ago #563

  • leosoft
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Just installed and tested Teslascada2 today. I tried to read some tags thru TCP; but no data comes thru.
I have two different programs I use very often, since over a year, to read many meters and registers without any problem.
. It is not clear to me if "Offset" is relative to base 0 or 1 ?
. Would like to confirm: Holding Registers creates a Modbus read with FC= 3 and Input Registers creates a FC= 4 reading ?
. Defined my server at local ip (1192.168.1.237) port= 502 Poll= 3000 type= TCP Consecutive reg RTU via TCP No function 6
I tried various combinations but absolutely no response... Some registers are float, some Int32 with inverted words...
Any idea of what should be done, or check over Windows 7, to obtain a Modbus response?
Thanks for your help
Gabriel
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Modbus TCP 6 months 2 weeks ago #565

  • fatkhrus
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Dear Gabriel,
Answers to your questions:
- Offset is relative to base 0.
- Function code for reading Holding Register = 3, for Input Registers = 4.
- Settings for Modbus sever look correct.
Do you use TeslaSCADA2 Runtime to connect to your device? What message do you? "Can not connect to the server" or "Connection Lost"? If "Can not connect to the server" try to ping your device. If "Connection Lost" try to check registers you read. I recommend to use WireShark to check Requests and Responses.

Best regards,
Ruslan
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Modbus TCP Configuration 5 months 3 days ago #628

  • ghesilviu
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Dear Ruslan,
I tested a Modbus connection and there is a problem reading analogue addresses AI_00 - AI_03
Digital DI addresses are read correctly.....
I have configured according to the attached photo ....
Where do I get wrong?
Thanks
Silviu
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Modbus TCP Configuration 5 months 3 days ago #629

  • fatkhrus
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Dear Silviu,

You should choose Input register in Pointer type, not Holding Register.

Best regards,
Ruslan
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