Technical data

Note
The CPU registers a power down (NAU or PEU) even when this
occurs in the STOP mode. If you then trigger a MANUAL
WARM RESTART, the CPU calls OB 22 before OB 21. If,
instead, you trigger a MANUAL COLD RESTART, the previous
events are ignored by the CPU and OB22 is not called.
RETENTIVE MANUAL
COLD RESTART
If the parameter "RETENTIVE COLD RESTART" is entered in the
data block DX 0, after processing OB 21, the system program then
goes through a COLD RESTART (the CPU resumes program
execution with the first STEP 5 statement in OB 1 or
FB 0). The signal states of the flags, IPC flags, semaphore and the
block address list (DB 0) are retained.
OB 22 AUTOMATIC WARM RESTART or RETENTIVE AUTOMATIC
COLD RESTART:
When the CPU executes an AUTOMATIC WARM RESTART or a
RETENTIVE AUTOMATIC COLD RESTART, the system program
calls OB 22 once. Here you can store a STEP 5 program which
executes specific actions once before restoration of program execution
previously interrupted in RUN.
AUTOMATIC WARM
RESTART
When the power is restored, the CPU carries out the system functions
mentioned above and attempts to continue the program from the point
at which it was interrupted.
If it is loaded, OB 22 is called first. After OB 22 is processed, cyclic
program execution resumes with the next statement after the point at
which it was interrupted.
After a power failure and subsequent restoration of power, the
following conditions apply:
•• The BASP signal (disable command output) remains active while
the remaining cycle is processed. It is cleared at the beginning of
the next complete cycle.
•• The process output image is reset at the end of the remaining cycle.
RETENTIVE AUTOMATIC
COLD RESTART
If the parameter "RETENTIVE COLD RESTART" is entered in the
data block DX 0, after processing OB 22, the system program then
goes through a COLD RESTART (the CPU resumes program
execution with the first STEP 5 statement in OB 1 or FB 0). The
signal states of the flags, IPC flags, semaphore and the block address
list (DB 0) are retained.
RESTART Mode
CPU 928B Programming Guide
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