Beckhoff EPP1 Series, Руководство пользователя

Страница: 71 / 92

Commissioning/Configuration
EPP1xxx 71 Version: 1.4
5.2 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
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