Siemens SIMATIC S7-1200 Manual page 57

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 output terminals of the PLC0. In RUN mode, the CPU system
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. After
each program execution cycle, the CPU transfers the new output state reaction stored in the
process-image register to the wired output terminals.
You can specify an immediate write of a physical output using ":P" following the tag for an
output (such as "Motor_On:P" or "Q3.4:P"). For an immediate write, the bit data values are
written to the process image output and directly to the physical output.
Coils are not restricted to the end of a network. You can insert a coil in the middle of a rung
of the LAD network, in between contacts or other instructions.
NOT contact inverter
(LAD)
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.
For FBD programming, you can drag the "Negate binary input" 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.
AND box (FBD)
● All inputs of an AND box must be TRUE for the output to be TRUE.
● Any input of an OR box must be TRUE for the output to be TRUE.
● An odd number of the inputs of an XOR box must be TRUE for the output to be TRUE.
In FBD programming, the contact networks of LAD are represented by AND (&), OR (>=1),
and exclusive OR (x) box networks where you can specify bit values for the box inputs and
outputs. You may also connect to other logic boxes and create your own logic combinations.
After the box is placed in your network, you can drag the "Insert binary input" tool from the
"Favorites" toolbar or instruction tree and then drop it onto the input side of the box to add
more inputs. You can also right-click on the box input connector and select "Insert input".
Box inputs and output can be connected to another logic box, or you can enter a bit address
or bit symbol name for an unconnected input. When the box instruction is executed, the
current input states are applied to the binary box logic and, if true, the box output will be true.
Easy Book
Manual, 11/2009, A5E02486774-01
5.3 Easy to use the powerful programming languages
AND box with one inverted
logic input (FBD)
OR box (FBD)
Programming concepts made easy
AND box with inverted logic input
and output (FBD)
XOR box (FBD)
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