Latch Function (Only In Standard Mode) - Siemens SIMATIC ET 200S Operating Instructions Manual

4.6.7

Latch Function (Only in Standard Mode)

Description
You use the latch function to freeze the current encoder value of the 1SSI at an edge at the
digital input (DI).
The encoder value can thus be evaluated on an event-dependent basis.
A frozen encoder value is identified by the set bit 31 and is preserved until the termination of
the latch function.
The frozen encoder value is entered at the feedback interface at the position of the cyclically
recorded value and assigned the identifier "Bit 31 set."
Note
Direction determination, comparison, and error monitoring also take place when the encoder
value is frozen.
Prerequisites for Using the Latch Function
• You must have specified which edge (rising and/or falling) at the digital input freezes the
• You specify that the latch function that is coupled to the digital input is switched on.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
encoder value.
1SSI
4.6 Functions of the 1SSI
237