The Display output contains the PLC date and time. The Display_NTPC type is a predefined structure comprising a DT type element and an INT type element. This gives us:

• Display.DT_value containing the date,

• Display.Milisecond containing the number of milliseconds of this date, as the second is the minimum measurement unit for the DT format.

The Calc output contains the date and time acquired on an NTP server (as in a Display variable, only with a different format). The Calc_NTPC type is a predefined structure comprising a UDINT type element and an INT type element. This gives us:

• Calc.Seconds containing the number of seconds passed since January 1, 1980, at 00:00.

• Calc.Fraction_Second containing the number of milliseconds to add for the precision of the result to be around a millisecond.

The low byte is managed by the CPU. When the low byte is set to 1:

• the clock value is not available

• the date and time are not updated within last two minutes

When the low byte is set to 0:

• the date and time are updated within the last two minutes

• the date and time are acceptable

If the processor is NTP client, the high byte is managed by the Ethernet module. When the high byte is set to 1, the clock value transferred to CPU is not acceptable.

When the high byte is set to 0, the updated date/time received from server and sent to module is:

• within two minute time interval

• acceptable (10 ms or less error)

For a valid time in CPU, the low and high bytes of the STATUS parameter must be set to 0. If not, it generates a runtime error (below).