Timestamp inputs (EPP1258)

Timestamp inputs are digital inputs that log the times of signal edges with high temporal resolution.

A timestamp input provides two timestamps in variables:

Timestamp of the last recorded rising signal edge
Timestamp of the last recorded falling signal edge

At each signal edge the corresponding variable is overwritten with the current timestamp.

Variables are always read in by the PLC at the beginning of a PLC cycle. If several signal edges occur within a PLC cycle, the PLC receives only the timestamps of the last rising and the last falling signal edge at the beginning of the following PLC cycle.

Application Note DK9222-0211-0021 contains further information on timestamp inputs.

Variables in the process image

Variable		Contents
Input X01	Input X02	Contents
Channel 1 Input	Channel 2 Input	Signal level that is currently present at the digital input
Latch Status0	Latch Status1	Information as to whether the last recorded signal edge was a rising or a falling signal edge: Bit 3: Bit 3 is set on rising signal edge Bit 3 is cleared on falling signal edge
Latch LatchPos0	Latch LatchPos1	Timestamp of the last recorded rising signal edge. Representation: 1 ns / LSB
Latch LatchNeg0	Latch LatchNeg1	Timestamp of the last recorded falling signal edge. Representation: 1 ns / LSB