Siemens SIMATIC S7-1200

Technology instructions
10.1 Counting (High-speed counters)
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
569
10.1.2.3
Capture function
You use the Capture function to save the current counter value with an external reference
signal. When configured and enabled by the "HSC_Count.EnCapture" bit, the Capture
function causes the current count to be captured on the occurrence of an external input
edge. The Capture function is effective regardless of the status of the internal gate. The
program saves the unchanged counter value when the gate is closed. After executing the
CTRL_HSC_EXT instruction, the program stores the captured value in
"HSC_Count.CapturedCount".
The figure below shows an example of the Capture function configured to capture on a rising
edge. The Capture input does not trigger a capture of the current count when the
"HSC_Count.EnCapture" bit is set false through the CTRL_HSC_EXT instruction.
Note
The configured input filters delay the
control signal of the digital input.
This input function can only be used when the HSC is configured for Count mode.
Refer to Input functions (Page 578) for information on how to configure the Capture function.