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4.2
STOP Mode
4.2.1
SOFT STOP
Initialization of
communication
(OB 38)
Start-up monitoring of
OB 38
Cyclic communication
(OB 39)
CPU 948 Programming Guide
C79000-G8576-C848-04
The CPU 948 has two different STOP modes, the "hard" STOP and
the "soft" STOP (= CPU capable of communication).
The SOFT STOP mode has the following features:
The CPU can communicate: the system program calls organization
block OB 38 once after POWER UP (COMMUNICATION
START-UP level in SOFT STOP) and then calls OB 39
(COMMUNICATION level in SOFT STOP).
To initialize communication, the system program calls OB 38 as the
user interface.
OB 38 is only called after POWER UP . The call is not
dependent on the type of start-up (AUTOMATIC COLD
/AUTOMATIC WARM RESTART) set in data block DX 0.
The time required for the execution of OB 38 is not monitored by the
system program. You can, however, abort execution by changing the
mode selector to STOP.
If an error occurs in OB 38, its execution is aborted and OB 39 is
called if it exists.
If the cyclic program is interrupted causing a change to the SOFT
STOP mode, OB 39 is called as the user interface.
If the interruption of the cyclic program means that a handling block
(communication) is not completely executed, it is possible and
permitted to re-call the same block or the same block type in OB 39
(e.g. SEND).
STOP Mode
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