User Manual
Chapter 10
GFK-1503F
Jan 2020
Instruction Set Reference
131
Input/
Output
Choices
Description
ST
I, Q, M, T, SA, SB,
SC, G, R, AI, AQ
ST contains the first bit or word of the shift register. For
SHFR_BIT, any discrete reference may be used; it does not need
to be byte aligned.
ok
flow, none
OK is energized whenever the function is enabled, and R is not
enabled.
Q
I, Q, M, T, SA, SB,
SC, G, R, AI, AQ
Output Q contains the bit or word shifted out of the shift
register. For SHFR_BIT, any discrete reference may be used; it
does not need to be byte aligned.
CAUTION
The use of overlapping input and output reference address ranges in multi-word functions
is not recommended; it may produce unexpected results.
Example 1:
In the example, the shift register operates on register memory locations %R0001 through
%R0100. (%R0001 is defined as type Word of length 100). When the reset reference CLEAR
is active, the Shift Register words are set to zero.
When the NXT_CYC reference is active and CLEAR is not active, the word from output status
table location %Q0033 is shifted into the Shift Register at %R0001. The word shifted out of
the Shift Register from %R0100 is stored in output %M0005.
Figure 107
Example 2:
In this example, the Shift Register operates on memory locations %M0001 through
%M0100. (%M0001 is defined as type Boolean of length 100). When the reset reference
CLEAR is active, the Shift Register function fills %M0001 through %M0100 with zeros.
When NXT_CYC is active and CLEAR is not, the Shift Register function shifts the data in
%M0001 to %M0100 down by one bit. The bit in %Q0033 is shifted into %M0001 while the
bit shifted out of %M0100 is written to %M0200.