Technical data

Force Using the FORCE function you can set the output bytes of the
programmable controller to a particular signal state directly (avoiding
the process image) or you can recognize process interface modules
(digital peripherals 0 to 127) that do not acknowledge (message on the
PG). You can check and directly control the process devices
(actuators e.g. motor, valve) supplied with signals by the outputs.
Note
The "force" function is only permitted in the stop mode.
Function sequence When you call the function in the STOP mode, the command output
disable function is cancelled (BASP = inactive). The
whole digital
peripheral area (F000H to F07FH) is cleared, and the value "0" is
written to each address. You cannot interrupt this function while the
peripherals are being cleared.
The peripheral outputs are forced in bytes directly and without
affecting the process output image.
In multiprocessor operation, you can force
all peripheral outputs
(regardless of the peripheral assignment in DB 1).
When the function is active (message "End of force fct" on the PG),
you can perform a COLD RESTART or a MANUAL WARM
RESTART. If the CPU once again changes to the STOP mode, you
can use the force function again. The process interface output modules
are
not cleared in this case.
Terminating the function You terminate the function by pressing the break key on the PG. The
command output disable function is once again activated
(BASP LED = on).
Force variables Using the PG function FORCE VARIABLES, you can change the
values of operands (process variables) once. You can do this in any
CPU mode. You can specify all process variables. If you attempt to
access an address in the range of the process image for which there is
no I/O, no ADF is triggered.
The modification becomes effective asynchronously to the system
checkpoints, i.e. not till the end of the cycle. Remember that the
forced values can be overwritten later (e.g. by the user program or
when the process image is updated).
Note
The PG forces the I, Q and F process variables in bytes and the
DW, T and C variables in words.
If you force
several operands, the modified bytes (for DW, T
and C the words) are changed in the CPU memory, distributed
over several function calls.
11
PG Functions
CPU 928B Programming Guide
C79000-B8576-C898-01
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