Internal Gate - Siemens SIMATIC ST-1500 Function Manual

The basics of counting, measurement and position detection
2.4 Basics of counting (digital input modules)
2.4.4.3

Internal gate

Internal gate
The internal gate is open if the software gate is open and the hardware gate is open or has
not been configured. The status of the internal gate is indicated by the STS_GATE feedback
bit. See the module's device manual for information on the design of the control and
feedback interface.
If the internal gate is open, counting is started. If the internal gate is closed, all other count
pulses are ignored and counting is stopped.
If you want to control a counting process with the hardware gate only, the software gate must
be open. If you do not configure a hardware gate, the hardware gate is considered to be
always open. In this case, you open and close the internal gate with the software gate only.
Hardware gate
Open/not configured
Open/not configured
closed
closed
The internal gate can also be automatically closed upon violation of a counting limit. The
software or hardware gate must then be closed and reopened to continue counting.
86
Software gate
open
closed
open
closed
Internal gate
open
closed
closed
closed
Counting, measurement and position detection
Function Manual, 12/2017, A5E32009889-AG