LOGO! Manual
A5E00380835-01
214
Functional description
The function reads the value at input In with a positive edge
(0 to 1 transition) at input Trg (Trigger).
This value is applied to shift register bit S1 or S8, depend-
ing on the shifting direction:
Shift up: The value at input In is set at S1; the previous
value at S1 is shifted to S2; the previous value at S2 is
shifted to S3 etc.
Shift down: The value at input In is set at S8; the pre-
vious value at S8 is shifted to S7; the previous value at
S7 is shifted to S6 etc.
Output Q returns the value of the configured shift register
bit.
If retentivity is disabled, the shift function restarts at S1 or
S8 after a power failure. When enabled, retentivity always
applies to all shift register bits.
Note
The special function shift register can be used only once in
the circuit program.
Timing diagram
Trg
In
Q
Dir
S1 0 1 0 1 1 0 1
S2 0 0 1 0 1 1 1
S3 0 0 0 1 0 1 0
S4 0000101
S5 1 0 0 0 0 1 0
S6 1 1 0 0 0 0 0
S7 0 1 1 0 0 0 0
S8 0 0 1 1 0 0 1
S4 = Q (example)
Shift up Shift down
LOGO! functions
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