Modbus Server Smoothing

[emaddocks]

Hi,

I would like to be able to apply smoothing to our Modbus Server DPEs. We are not in control of the data being written to the DPEs via the Modbus Server driver but we want to be able to smooth out noisy signals on our end.

The smoothing config is unable to be added to the DPEs used in the Plant Model. I assume this is because the the DPEs don't have an address config and thus an associated driver to do the smoothing. The error message seems to indicate a driver number 6 but our system does not have a driver numbered 6:

Code: Select all

WCCOAui (18), 2025.03.25 15:39:25.688, SYS, SEVERE, 38, Message could not be sent, DP: PSS:Section1.state.powerStatus:_smooth.._type, MAN: (SYS: 0 Driver -num 6 CONN: 1), Could not send message DP_MSG_COMPLEX_VC #240480103

I haven't been able to find anything in the online help. The possible config entries for [modsrv] and [all drivers] don't seem relevant either.

Does anyone know if it is possible to apply smoothing to DPEs that are used in a Plant Model for a Modbus Server connection? I want to avoid having to implement custom logic to do the smoothing ourselves and write it to a separate non Plant Model DPE.

We are running WinCC OA 3.18 P24 on RHEL 8.8.

Cheers
Eric

[leoknipp]

A _smooth config can only be added for DP elements which are related to a driver. A Modbus server is not a "driver" from the technical point of view in WinCC OA.
If you run the Modbus server you will see that it is not added to the list of running drivers in the element _Connections.Driver.ManNums. As it is defined as manager type "Device" it is added to _Connections.Device.ManNums.

The _smooth config is handled by a driver and it only works for values which are received from the peripheral device and send to the Event Manager.

If you want to avoid that values are send with the Modbus server to a connected client you must implement some business logic on your own which prevents the dpSet on the original value.

Best Regards
Leopold Knipp
Senior Support Specialist

[emaddocks]

Thanks Leopold. I thought that would be the case