Siemens SIMATIC S7 - Page 50

Activating inputs IN1 and IN2
The two inputs IN1 and IN2 must be activated so their positive state is 0.
Example
For non-equivalent signals, you have to negate the input (IN1 or IN2), which you
have assigned the positive state 1 for the sensor signal . You must also OR the
sensor signal with the QBAD tags of the corresponding F-I/O DB, so that signal
state 0 is applied to input IN1 or IN2 (after the negation), if substitute values are
output.
F_1
oo
2DI
w
ith
nonequ
i
va
l
ence s
i
gna
l
s
"Sensor
_
2
_
(close)"
"Sensor
_
1
_
(open)"
Comments:
Timing Diagram F_1oo2DI
If ACK_NEC = 1 is set:
DISCTIME
Q
DISCTIME
DISCTIME DISCTIME
IN1
IN2
Q
DISC_FLT
A
CK_REQ
A
CK
DIAG (Bit1)
DIAG (Bit2)
Product Information for the S7 Distributed Safety, Configuring and Programming Manual
50 A5E00169432-02