Program instructions
7.13 Program control
S7-200 SMART
346 System Manual, V2.3, 07/2017, A5E03822230-AF
The
instruction loads the SCR and logic stacks with the value of the
S bit referenced by the instruction.
The resulting value of the SCR stack either energizes or de-energizes the
SCR stack. The value of the SCR stack is copied to the top of the logic
stack so that LAD boxes or output coils can be tied directly to the left
power rail and no preceding contact instruction is required.
The
instruction identifies the SCR bit to be enabled (the next S_bit
to be set). When power flows to the coil or FBD box, the CPU turns on the
referenced S_bit and turns off the S_bit of the LSCR instruction (that ena-
bled this SCR segment).
The
(conditional SCR end) instruction, for STL and FBD, termi-
nates execution of the SCR segment when enabled. For LAD, a condi-
tional contact placed before a
coil performs the conditional SCR
end function.
The
(unconditional SCR end) instruction, for STL and FBD, termi-
nates execution of the SCR segment. For LAD, an SCRE coil connected
directly to the power rail performs the unconditional SCR end function.
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