• Replies 8 replies
  • Subscribers 581 subscribers
  • Views 604 views
  • Users 0 members are here
Options
Related

Negative value in DNPr not coming

Bhadresh

I am trying Schneider NOR module to read data over DNPr protocol. Has anyone have tried to read negative value from NOR in CitectSCADA ?

As i am not getting value in negative. Instead its displaying 65535 like that value. I tried to read same tag in Kepserver and datatype with Short datatype and its reading negative value properly. Even Kepware also not able to read same negative value using Long/read (Which only support for Analog Input in Citect).

Any idea about this or there is limitation of driver that we are not able to read INT datatype using DNPr protocol.

Parents
  • Can you check which DNP object group and variant number is being used for this variable?
    It should be Object group 30 or 32 (analog input) and Variant number 2 or 4 (16-bit values).
    If the NOR module transmits the value as variant 1 or 3 it tells the Citect driver to treat the variable as 32-bit and then you will not be able to read negative values.

    So I don't think it is a driver bug, but rather a configuration issue on the data source end (NOR module).
    Setting the data type to Single in Kepware forces the data to be seen as 16-bit INTs, so it overrules the DNP3 data type.

    After browsing the NOR manual I found that you need to set Static Variation to "g30v2" or "g30v4" and Event Variation to "g32v2" or "g32v4" for 16-bit integer analog inputs.
Reply
  • Can you check which DNP object group and variant number is being used for this variable?
    It should be Object group 30 or 32 (analog input) and Variant number 2 or 4 (16-bit values).
    If the NOR module transmits the value as variant 1 or 3 it tells the Citect driver to treat the variable as 32-bit and then you will not be able to read negative values.

    So I don't think it is a driver bug, but rather a configuration issue on the data source end (NOR module).
    Setting the data type to Single in Kepware forces the data to be seen as 16-bit INTs, so it overrules the DNP3 data type.

    After browsing the NOR manual I found that you need to set Static Variation to "g30v2" or "g30v4" and Event Variation to "g32v2" or "g32v4" for 16-bit integer analog inputs.
Children
No Data
© 2025 AVEVA Group Limited or its subsidiaries. All Rights Reserved.