107BOnline and diagnostic tools
14.10 Monitoring and modifying values in the CPU
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
649
If the CPU is executing the user program from a write-protected memory card, you cannot
initiate or change the forcing of I/O from a watch table because you cannot override the
values in the write-protected user program. Any attempt to force the write-protected values
generates an error. If you use a memory card to transfer a user program, any forced
elements on that memory card will be transferred to the CPU.
Note
Digital I/O points assigned to HSC, PWM, and PTO cannot be forced
The digital I/O points used by the high-speed counter (HSC), pulse-width modulation (PWM),
and pulse-train output (PTO) devices are assigned during device configuration. When digital
I/O point addresses are assigned to these devices, the values of the assigned I/O point
addresses cannot be modified by the force function of the watch table.
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Startup
RUN
A
The clearing of the I memory area is not
affected by the Force function.
①
While writing Q memory to the physical
outputs, the CPU applies the force value as
the outputs are updated.
B
The initialization of the outputs values is
not affected by the Force function.
②
When reading the physical inputs, the CPU
applies the force values just prior to copying
the inputs into I memory.
C
During the execution of the startup OBs,
the CPU applies the force value when
the user program accesses the physical
input.
③
During the execution of the user program
(program cycle OBs), the CPU applies the
force value when the user program accesses
the physical input or writes the physical
output.
D
The storing of interrupt events into the
queue is not affected.
④
Handling of communication requests and self-
test diagnostics are not affected by the Force
function.
E
The enabling of the writing to the
outputs is not affected.
⑤
The processing of interrupts during any part of
the scan cycle is not affected.
