Table of Contents
Advertisement
10.2.5
System Start-Up
COLD RESTART
WARM RESTART
CPU 948 Programming Guide
C79000-G8576-C848-04
If you require multiprocessor communication, then all CPUs involved
must go through the same STOP-RUN transition (= RESTART), i.e.
all the CPUs go through a COLD RESTART or all CPUs go through a
WARM RESTART.
You must make sure that the restart of at least all the CPUs involved
in the communication is uniform (see Section 10.1.7), in the
following ways:
• • direct operation (front switch, programmer),
• • parameter assignment (DX 0)
and/or
• • programming (using the special function organization block OB 223
"stop if non-uniform restarts occur in the multiprocessor mode")
In organization block OB 20 (COLD RESTART) only one CPU must
set up the buffer (in the COR 923C) using the INITIALIZE function.
Any existing data is lost.
Following this, i.e. during the RESTART, you can call the SEND,
SEND TEST, RECEIVE, RECEIVE TEST functions in the individual
CPUs. With appropriate programming, you must make sure that this
only occurs after the buffer in the coordinator has been correctly
initialized.
On completion of the RESTART, i.e. in the RUN mode, the user
program is processed from the beginning, i.e. from the first operation
in OB 1.
You must not use the INITIALIZE function in the organization blocks
OB 21 (MANUAL WARM RESTART) and OB 22 (AUTOMATIC
WARM RESTART). Calling the SEND, SEND TEST, RECEIVE,
RECEIVE TEST functions can cause problems (refer to the following
sections).
On completion of the WARM RESTART, i.e. in the RUN mode, the
user program is not processed from the start, but from the point at
which it was interrupted. The point of interruption can, for example,
be within the SEND function.
Multiprocessor Communication
10 - 21
Advertisement
Table of Contents
