Gate Control With Incremental Or Pulse Encoder; Software Gate; Hardware Gate - Siemens SIMATIC ST-1500 Function Manual

2.2 Basics of counting, measuring and position input (TM Count, TM PosInput, Compact CPU)
2.2.5

Gate control with incremental or pulse encoder

Many applications require counting processes to be started or stopped in accordance with
other events. In such cases, counting is started and stopped using the gate function.
The technology modules have two gates for each channel. These define the resulting
internal gate:
● Software gate
● Hardware gate
2.2.5.1

Software gate

The software gate of the channel is opened and closed with the control bit (Page 185)
SW_GATE. The status of the software gate is indicated by the feedback bit (Page 188)
STS_SW_GATE .
2.2.5.2

Hardware gate

The hardware gate is optional. You open and close the hardware gate by means of signals
at the configured digital inputs of the channel.
Note
The configured input filters delay the control signal of the digital input.
The status of a DIm digital input is indicated by the respective feedback bit (Page 188)
STS_DIm .
Level-triggered opening and closing of the hardware gate with a digital input
The figure below shows an example of level-triggered opening and closing with a digital
input. The digital input is configured to be active with high level:
As long as the digital input is active, the hardware gate is open and the count pulses are
counted. The hardware gate is closed when the digital input becomes inactive. The counter
value stays constant and ignores any further count pulses.
Counting, measurement and position detection
Function Manual, 12/2017, A5E32009889-AG
The basics of counting, measurement and position detection
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