Hi! i have a WinCC OA v13 sp13
I'm using a Modus Driver and some PLCS connected.
All tags are addressing to PLC using Polling or Single Query and all has check the option Low Level comparation ( option to prevent each time of polling the the timestamp of the real value change if the value is the same).
In the value of tag i have the same value ( i'm testing with a modsim without changes) but the timestamp of the value change each time of polling...why?
If this change, all CTRL Managers receive the value and execute some scripts that they are not necessary.
I send some files where you can see that.
Problem in Low Level comparation
- RudiKreiner
- Posts:198
- Joined: Mon May 16, 2011 2:10 pm
Re: Problem in Low Level comparation
Are you sure that your floating point numbers really aren't changing? The low level comparision really compares the bit pattern of the numbers so that even a very small change results in an event.
The best way to see this is to look at the values in hex format in your plc, or to change the number format to display very many decimal places in the para.
To avoid this you can configure the smoothing config as well to only allow changes that are of numerical significance to be passed through the driver to the event manager.
The best way to see this is to look at the values in hex format in your plc, or to change the number format to display very many decimal places in the para.
To avoid this you can configure the smoothing config as well to only allow changes that are of numerical significance to be passed through the driver to the event manager.
- rglock
- Posts:19
- Joined: Wed Sep 08, 2010 9:54 am
Re: Problem in Low Level comparation
From the corresponding service request to the WinCC OA customer care team:
It was an address, where individual bits whrer extracted from a register using subindices.
With such a configuration you have to consider the following when using low level comparison:
* Since always the whole register have to be read and low level comparison is applied to "raw" data,
the comparision is done on the whole register.
This means you get an update on the DPE if any of the bits change in the register.
You can avoid this by adding smooth config for each of the DPEs.
*Can you also check that low level comparision is activated for all address, which targets in the same register,
because otherwise again the whole register will pass.
It was an address, where individual bits whrer extracted from a register using subindices.
With such a configuration you have to consider the following when using low level comparison:
* Since always the whole register have to be read and low level comparison is applied to "raw" data,
the comparision is done on the whole register.
This means you get an update on the DPE if any of the bits change in the register.
You can avoid this by adding smooth config for each of the DPEs.
*Can you also check that low level comparision is activated for all address, which targets in the same register,
because otherwise again the whole register will pass.