Bit Test Operations - Siemens SIMATIC S5-95F Manual

S5-95F
8.2.3

Bit Test Operations

Bit test operations scan digital operands bit by bit and affect them. Bit test operations must always
be at the beginning of a logic operation. Table 8-12 provides an overview of these operations.
Operation Operand
TB
TBN
SU
RU
ID
T
C
D
RS 1
RS applies only to TB and TBN
1
Table 8-13 shows how the RLO is formed during the bit test operations "TB" and "TBN".
example for applying the bit operations follows the table.
Signal state of the bit in
the operand indicated
Result of logic operation
EWA 4NEB 812 6210-02
Table 8-12. Overview of Bit Operations
Test a bit for signal state "1"
A single bit is scanned regardless of the RLO. The RLO is affected
according to the bit's signal state (see Table 8-13).
Test a bit for signal state "0"
A single bit is scanned regardless of the RLO. The RLO is affected
according to the bit's signal state (see Table 8-13).
Set a bit unconditionally
The addressed bit is set to "1" regardless of the RLO. The RLO is
not affected.
Reset a bit unconditionally
The addressed bit is set to "0" regardless of the RLO. The RLO is
not affected.
Parameter
Table 8-13. Effect of "TB" and "TBN" on the RLO
Operation
Meaning
0.0 to 127.15
0.0 to 127.15
0.0 to 255.15
0.0 to 255.15
STEP 5 Operations
TB TBN
0 1 0
0 1 1
An
1
0
8-41