Modbus TCP writing issue

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2 posts • Page 1 of 1
walterd
Posts:38
Joined: Wed Mar 13, 2013 10:39 pm

Modbus TCP writing issue

Post by walterd »

I am using Modbus for reading and writing booleans. While reading is working fine, I have problems with writing. The error I get is :

WCCOAmod (1), 2018.03.02 08:52:35.505, PARAM,SEVERE, 54, Unexpected state, DP: (Type: 223 Sys: 1 Dp: 1204 El: 59 : _original.._value), MAN: (SYS: 1 Driver -num 1 CONN: 1),
Missing transformPtr for M.1.5.9840

The configuration is write single coils , type is set to boolean. The other PLC parameters are the same as reading boolean (single coils).

What am I doing wrong ?
Thanks
Walter

mkerk
Posts:75
Joined: Wed Oct 20, 2010 12:25 pm

Re: Modbus TCP writing issue

Post by mkerk »

Hi,
Could you please check again the configuration of the address-config. Your are using the Function code 5. for this you need the following:

1- The Type of the WinCC OA Datapointelement must be bit.
2- The type of Transformation in the address config must be “booleanas byte” and not “boolean”!

Please refer also to the WinCC OA documentation “Modbus/TCP driver ? Mdbus/TCP driver details ? Transformations” for detailed information about which transformations is compatible with which the function code.

BR,
Mousser

2 posts • Page 1 of 1