Problems to display correct time stamp in graphs and tables


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Dear Sirs,

I developed an application using DF 5.83 in which I read some modbus registers from a data logger using Modbus TCP protocol. Information is read correctly, but time stamp assigned to readings is not correct,i.e. it does not correspond to PC's clock. When I first start the application time stamp matches PC's clock, but as time goes by, time stamp DaqFactory assigns significatively goes behind ("delays") PC clock. For example, when I restarted application yesterday at 15:00 hrs, time stamp assigned to first reading was ok (15:00), but this morning at 11:00 AM, Daq Factory assigned a time satmp of 12/12/2009 20:30 hrs.

The application is running on a Dell Optiplex 9600 (4 GB RAM) with Windows XP Professional Service pack 3. I am attaching the file I created. I would appreciate if you let me know your suggestions on how to solve this problem.

Thanks. Sincerely, Jes


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Actually, the problem is with your computer. Either the system is overclocked, or some other non-standard installation is causing the high precision clock not to be accurate. We see this in about 1 in every 2000 or so DAQFactory installations. Fortunately, there is an easy way around it, and that is to use the low precision clock. There is a dll called usertime.dll that you can put in your DF directory that will cause it to use this clock. You can find all the details at this post: Note that the low precision clock is precise only to about 15ms, and will adjust for DST and any other system clock changes. These clock changes can cause sequences to hang, and alarms to inadvertantly fire if your system is not designed right (i.e. looks at data age without taking into account these changes.

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