Fail-Safe Blocks
Fail-Safe Systems
8-100 A5E00085588-03
Error Information in Diagnostic Buffer
Error Code (W#16#...) Description
0x75D9
Invalid REAL number
0x75DA
Error in the safety data format (error due to online modification of the
Safety Program or internal CPU fault)
8.9 Flip-Flop Blocks
Block Description
F_RS_FF RS flipflop, resetting dominant
F_SR_FF SR flipflop, setting dominant
8.9.1 F_RS_FF
Function
The block executes the function of an RS flipflop (resetting dominant).
The RS flipflop is reset if the signal state at the input R = 1 and at the input S =
0. The flipflop is set if the input R = 0 and the input S = 1. If the result of the logic
operation is 1 at both inputs, the flipflop is reset.
Truth Table
R S QN QNn
0 0 Qn-1 QNn-1
0110
1001
1101
I/Os
Name Data Type Explanation Default
Inputs:
R F_BOOL Reset 0
S F_BOOL Set 0
Outputs:
Q F_BOOL Output 0
QN F_BOOL Negating output 1
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