Timer Repeatability (consistency)

[homer4JC]

Our company is in the process of purchasing an automated system that will be performing soldering operations.  We are looking to validate the solder process, and as a result we are currently considering trying to "calibrate" the PLC timer.  I don't believe this is a value-added effort.  I am not so much concerned that the timer is accurate, but that the amount of time measured will not vary over time.  To put it another way, I'm not concerned whether or not the time elapsed is accurate, but that the measured time elapsed will remain the same over a period of years.  I was wondering if there is any documentation or studies out there that may have addressed this issue, and I would appreciate any help in finding an answer for me.

[support]

Thank you for your question. What is the range of elapsed time that is of interest? Is it in milliseconds, seconds, hours or days?

You could use the PLC's timer to measure elapsed time in 0.1 or 0.01 second resolution. But if the elapsed time is measured in seconds and minutes, then an accurate real-time-clock (preferably one that is synchronized to the Internet time server) will ensure that the measured elapsed time will forever be consistent.