Latch Function - Siemens SIMATIC ET 200S Operating Instructions Manual

3.6.7

Latch Function

Introduction
There are two latch functions:
• The Latch and Retrigger function
• The Latch function
The Latch and Retrigger Function
In order to use this function, you must first select it with the "Latch and Retrigger on Positive
Edge" Function DI parameter.
Figure 3-9
This function stores the current internal count of the 1Count5V/500kHz and retriggers
counting when there is a positive edge on the digital input.
This means that the current internal counter status at the time of the positive edge is stored
(latch value), and the 1Count5V/500kHz is then loaded again with the load value, from which
counting resumes.
The counting mode must be enabled with the SW gate before the function can be executed.
It is started with the (first) positive edge on the digital input.
The stored count rather than the current count is indicated in the feedback interface. The
STS_DI bit indicates the level of the latch and retrigger signal.
The latch value is preassigned with its RESET state (see RESET states table). It is not
changed when the SW gate is opened.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Latch and Retrigger with Load Value = 0
1Count5V/500kHz
3.6 Count Modes
137