Siemens SIMATIC S7-1200 Manual page 98

Programming made easy
6.3 Powerful instructions make programming easy
Output coil
● If there is power flow through an output coil, then the output bit is set to 1.
● If there is no power flow through an output coil, then the output coil bit is set to 0.
● If there is power flow through an inverted output coil, then the output bit is set to 0.
● If there is no power flow through an inverted output coil, then the output bit is set to 1.
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 on the PLC. 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)
98
Inverted output coil
AND box with one inverted
logic input (FBD)
OR box (FBD)
AND box with inverted logic input and
output (FBD)
XOR box (FBD)
Manual, 11/2011, A5E02486774-04
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