dpGet generates EV - Driver messages?

[pablo.chamorro]

Hello,

We have a doubt about dpGet function. Does it generates EV - Driver messages?

We make a simple test:
One DPE with a 10 seconds poll group (S7 Connection)
One script with a loop gets and prints each second it's _online .._ value

result: value printed changes only each 10 seconds.

Our conclusion: If dpGet asked Driver it's value would change each second. dpGet does not generate driver message because reads values of data point attributes.


We make a complex test:
To get a connections control we use a control script were we read ( dpGet) _address attributes (Driver, reference, connection) to write (dpSet) on a DPE wich connections uses each panel.

We use S7Plus and S7 Driver.

Result: During the script generates a huge load of EV - Driver managers messages in both driver managers.

In a second complex test we read only DPTs that uses S7 Driver Manager and only this one got a huge load of EV - Driver manager messages.

Our conclusion: Somehow dpGet asks driver the _address attributes.

Basicaly we don't undersant why reading _address attributes generates EV - Driver messages if on the simple test doesn't change the value in each dpGet.

We use 3.17 P007

[leoknipp]

The driver related configs (_address, _smooth, _cmd_conv, _msg_conv) are stored in the driver during runtime.
If you want to get this information with a dpGet() the Event Manager has to send a message to driver to read the information.

You can possibly use a different approach to get the active addresses by using the _Driver<num>.AD.* elements.
To get more information please have a look at the WinCC OA Documentation: Reference tables --> Internal datapoint types --> _DriverCommon

Best Regards
Leopold Knipp
Senior Support Specialist

[pablo.chamorro]

Thanks for this explaination Leoknipp,

It's important to know it. We will take a look the possibility that you mentioned.

Thanks again.