Siemens LOGO! Series Manual page 246

LOGO! functions
4.4 Special functions list - SF
Functional description
The function reads the value at input In with a positive edge (0 to 1 transition) at input Trg
(Trigger).
If your LOGO! is a LOGO! 0BA6, this value is applied to shift register bit S1 or S8, depending
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
● Shift down: The value at input In is set at S8; the previous value at S8 is shifted to S7; the
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.
If your LOGO! is a LOGO! 0BA7, this value is applied to shift register bit Sx.1 or Sx.8
depending on the shifting direction, where "x" refers to the index number of the shift register
and the number after the decimal point refers to the bit number:
● Shift up: The value at input In is set at Sx.1; the previous value at Sx.1 is shifted to Sx.2;
● Shift down: The value at input In is set at Sx.8; the previous value at Sx.8 is shifted to
Output Q returns the value of the configured shift register bit.
If retentivity is disabled, the shift function restarts at Sx.1 or Sx.8 after a power failure. When
enabled, retentivity always applies to all shift register bits.
Note
There is only one shift register function block available for use in the circuit program in
LOGO! 0BA6.
There are a maximum of four shift register function blocks available for use in the circuit
program in LOGO! 0BA7.
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previous value at S2 is shifted to S3 etc.
previous value at S7 is shifted to S6 etc.
the previous value at Sx.2 is shifted to Sx.3 etc.
Sx.7; the previous value at Sx.7 is shifted to Sx.6 etc.
Manual, 04/2011, A5E03556174-01
LOGO!