Matching PLC and Qt C++ Client

I'm running a PLC simulation software and I have a client Qt, I get the data which is a temperature from the PLC and it's running its own internal operating system. At Qt client I'm running a thread every 1 second and I plot the temperature and the time, but its not accurate, how would I sync the data with the plc simulation software

In PLC

timer(IN := TRUE, PT:=tAbsoluteTime);
IF(timer.Q) THEN
rT := rT + 1/TIME_TO_REAL(tAbsoluteTime);
rOut := (1 - rT) * sPoints[iStartIndex].rTemperature + rT * sPoints[iEndIndex].rTemperature;
IF(rOUT > 0) THEN
bStartCounting := TRUE;
END_IF
timer.IN := FALSE;
rTickCount := rTickCount + 1;
END_IF
In Qt, I'm just running a timer with T = 1 Second and I'm reading rOut from it.

What PLC simulation software are you using?

How are you interfacing the PLC and the client?

How accurate do you need it to be?

In order to sync the data from the PLC, I would write the value to a variable and then increment an pointer to the next variable location for storage.

The software will then read pointer address. If it is greater then the first location then read the data value(s) and reset the pointer address.

Regards,

Update a transaction number in the PLC each time you update the temp. Then the PC can tell if the data has been updated and you can poll it more often than once a second.

andreahmed said:

At Qt client I'm running a thread every 1 second and I plot the temperature and the time

Click to expand...

a) Could you post a picture of the resulting plot?

timer(IN := TRUE, PT:=tAbsoluteTime);

Click to expand...

b) What value are you assigning to tAbsoluteTime? I'd assign something lower than 1/2 second.