Gate Control; Software Gate; Hardware Gate - Siemens SIMATIC ST-1500 Function Manual

2.4.4

Gate control

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 digital input modules have two gates for each counting channel. These define the
resulting internal gate:
● Software gate
● Hardware gate
Note
The hardware gate is not configurable for all digital input modules.
2.4.4.1

Software gate

The software gate of the channel is opened and closed with the SW_GATEcontrol bit.
See the module's device manual for information on the design of the control and feedback
interface.
2.4.4.2

Hardware gate

The hardware gate is optional. You open and close the hardware gate using signals at the
corresponding digital input.
Note
A configurable input delay delays the control signal of the digital input.
The status of a DIm digital input is indicated by the respective STS_DIm feedback bit. A
description of the control and feedback interface is available in the device manual for the
digital input module.
Opening and closing the hardware gate
The figure below shows an example of opening and closing with a digital input:
As long as the digital input is set, the hardware gate is open and the count pulses are
counted. The hardware gate is closed when the digital input is reset. 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
2.4 Basics of counting (digital input modules)
85