Siemens SIMATIC S7-1200 - Page 229

Basic instructions
8.1 Bit logic operations
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
229
NOT logic inverter
Table 8- 5 Invert RLO (Result of Logic Operation)
LAD
FBD
SCL
Description
NOT
For FBD programming, you can drag the "Invert RLO" tool
from the "Favorites" toolbar or instruction tree and then drop
it on an input or output to create a logic inverter on that box
connector.
The LAD NOT contact inverts the logical state of power flow
input.
• If there is no power flow into the NOT contact, then there
is power flow out.
• If there is power flow into the NOT contact, then there is
no power flow out.
Output coil and assignment box
The coil output instruction writes a value for an output bit. If the output bit you specify uses
memory identifier Q, then the CPU turns the output bit in the process-image register on or
off, setting the specified bit equal to power flow status. The output signals for your control
actuators are wired to the Q terminals of the CPU. In RUN mode, the CPU system
continuously scans your input signals, processes the input states according to your program
logic, and then reacts by setting new output state values in the process-image output
register. The CPU system transfers the new output state reaction that is stored in the
process-image register, to the wired output terminals.
Table 8- 6 Assignment and negate assignment
LAD
FBD
SCL
Description
out := <Boolean
expression>;
In FBD programming, LAD coils are transformed into
assignment (= and /=) boxes where you specify a bit ad-
dress for the box output. Box inputs and outputs can be
connected to other box logic or you can enter a bit ad-
dress.
You can specify an immediate write of a physical output
using ":P" following the Q offset (example: "%Q3.4:P").
For an immediate write, the bit data values are written to
the process image output and directly to physical output.
out := NOT <Boole-
an expression>;