Author Topic: Modbus TCP illegal datavalue  (Read 1857 times)

RobinH

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Modbus TCP illegal datavalue
« on: February 24, 2016, 06:26:03 AM »
Hi,

Im trying to read a value over modbus TCP. I have mapped 4001 to a register in my PLC.
When using DigitalPanelMeter1 i get the error Illegal Datavalue.

PLCAddressValue is set to 4001.

What am i doing wrong?


RobinH

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Re: Modbus TCP illegal datavalue
« Reply #1 on: February 24, 2016, 07:40:00 AM »
Found out that if I use default modbus mapping in my PLC, it will work up to register 9997 (49999).
I cannot access register 10 000 by this method. If i try 410000 it will only give illegal datavalue.
Default mapping means that all request are automatically applied to the PLC media, this is a quite dangerous method.


When deactivating default mapping and doing manual mapping it does not work.

By manual mapping it means that i can choose:

Partner media type
Partner start address
Partner range
Map to PCD type
Map to PCD start address
Map to PCD range
« Last Edit: February 24, 2016, 08:26:21 AM by RobinH »

Mvlawn

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Re: Modbus TCP illegal datavalue
« Reply #2 on: February 24, 2016, 09:44:31 AM »
What type/model of PLC are you using.

RobinH

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Re: Modbus TCP illegal datavalue
« Reply #3 on: February 24, 2016, 10:01:29 AM »
Hi,

I am using Saia Burgess PLC.
AdvancedHMI version 3.99C


RobinH

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Re: Modbus TCP illegal datavalue
« Reply #4 on: March 30, 2016, 06:33:31 AM »
Still having the same problem.

Any suggestions or solution?

Archie

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Re: Modbus TCP illegal datavalue
« Reply #5 on: March 30, 2016, 07:48:06 AM »
Try 40001 or 40002

servrbc

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Re: Modbus TCP illegal datavalue
« Reply #6 on: March 09, 2018, 02:54:25 PM »
Setting UnitId to 255 in TCP driver worked for me