What is IEC 1131 time?
In compliance with the standard IEC 1131 (EN 61131), time can be transmitted by a DWORD value. This time represents the number of seconds that have passed since 1st January 1970, 00:00.
A second DWORD with a microsecond counter that goes from 0 to 999999 is required by ibaPDA for higher accuracy. The counter is reset at the start of every second.
The time source can be any system, time server or PLC capable of generating such a time value.
IEC 1131 time settings
IEC 1131 time signal
Select the analog signal carrying the time value from the drop-down list.
Microsecond signal
Select the analog signal carrying the microsecond value from the drop-down list.
Time signal is local time/UTC time
Check the appropriate option according to the time format generated by the time source. If "Local time" was selected, ibaPDA will accept that time without any conversions. If "UTC" is selected, ibaPDA will convert the time to the local time according to the time zone settings of the computer.
Status
The status field shows the current status of the time synchronization. The time synchronization only works when the acquisition is running.
Difference between system time and received time
The received time is cyclically compared with the system time whereas deviation is determined. Depending on whether the difference is rather positive or rather negative, a corresponding frequency adjustment of the internal system clock is calculated.
System clock frequency adjustment
The value of the frequency adjustment has been determined from the difference between the system time and the received time. Thus, a system clock which is too fast or too slow is corrected.