How to manually execute single query for MODBUS

[burbaniec]

Hello,

I need to read values from my device via modbus.
I cannot use polling because I need to read memory addresses one by one.
How from control script I can call reading via modbus when communication is set up to "Single Query"?
I cannot find any method which does this.

Thanks in advance
Bartek

[leoknipp]

Hello,

executing a single query for a single input address is possible by setting the dp-element _DriverX.SQ (X has to be substituted with the driver number).
A description for the internal datapoint type _DriverCommon can be found in the reference tables in the WinCC OA online help.

How many input addresses are using single query in your project?
How often shall values be read from the PLC for these addresses?

Best Regards
Leopold Knipp
Senior Support Specialist

[burbaniec]

Hello,

Thank you for your reply.
It works perfectly!


There is around 30 addresses that I need to read.
I would like to read those values every 5 seconds.


Cheers
Bartek