read Siemens S7 CPU clock (WinCC) timestamp of alarm by 3rd party tool

[PackElend]

Hello,
there are many applications/devices around promoting that they can read an S7-400 without any modification to be done on the PLC.
This great as I could consume much more data through them (and investment is lower than going 100% through Siemens what is critical doing a data analytics upgrade on control system).

They say they can read any value (DB, in, -output etc. ).
My question is, which area I have to be queried to get the information when a signal is fired.
I want to read the timestamp of the alarm messages as it is usually shown in WinCC.

thank you

stefan

 

[RedSnake]

I'm not really sure what you're looking for here.
But in an S7-416 CPU you can set the clock via the S7 manager.
But that means the clock runs in the PLC and can go faster or slower.
If you want a "real" clock, you usually set the CPU's clock with the help of a CP443 Ethernet card and a clock sync server.
The time in the CPU: is written in ms which is then recalculated in different formats e.g. time of day and so on there are a couple of different ones to choose from.
But WinCC is a PC based HMI program, I may be wrong here, it has been a long time since I worked with WinCC, but I would think that the alarms that are displayed in a WinCC program get their timestamps from the PC and not from the PLC or maybe you can choose that.

Depending of what you are going to analyse and how important the exact time is I would think using the PC:s clock would be better if possible.
If the exact times stamp is not important but the duration between things the CPU clock time can be used.
If it synchronized via the ethernet there still would not be summer and winter time.

The PLC:s time can be written to a DB with a Special S7 Funktion Blocks as, Date and Time, Time of Day, Time etc and read from there.

Best Regards A



“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein