Like most microcontrollers / PLC's, the PAC Controller uses a real time chip for its date/time functions.
That chip will have some drift in its accuracy due to lots of reasons, not the least of which is temperature.
Thus, over time, the clock will be off by some amount.
If you are running PAC Display all the time, there is an option under the 'Configure' -> 'Runtime' -> 'Control Engine' tab to allow you to synchronize the control engine clock with the PC clock every day or so.
Also, when you double click on a control engine with PAC Terminal, there is an option there to click a button to 'Sync time to PC'.
But what if you do not have PAC Display running all the time on the same network as the controller, then what?
Well, thanks to the Ethernet connectivity smarts built into PAC controllers, you can, if you have Internet connectivity from the PAC, connect with a time server on the Internet and sync the clock from there..... Here is a chart to do just that.....
This is a screen shot of the chart we have been using for a while to do the time sync.
A quick over view shows that it checks to see if its 3am, and if so, open a comm handle with the NIST server, get the string back from it, parse it, convert the string to numbers and then use those numbers to set the clock.
Note, its critical that you have a gateway IP address set in the controller so it can find its way out to the net. (Set it in PAC Manager).
I have exported the chart from PAC Control Basic, ver 8.5 and attached it to this thread.
Just unzip the file once you download it and you will be ready to go.
All the variables are prefixed with 'time_', so it should be clear which ones are used in this chart.
With a bit of tweaking, there is no reason why this chart could not be made to work in Factory Floor.
If you have any other ways to do this important function, please let us all know.