Siemens CPU 948 User Manual

Timer processing
CPU 928B CPU 948
The timers are updated during
start-up.
The timers are only updated in
the RUN mode
(Reason: compatibility with
CPU 946/947)
FB 0 as cycle block
CPU 928B CPU 948
If no cycle block OB 1 exists, the
system program calls FB 0
cyclically, provided it is loaded.
Only OB 1 can be used for cyclic
processing. If you have
programmed FB 0, create an
OB 1 in which FB 0 is called.
Default priorities
CPU 928B CPU 948
Process interrupts have higher
priority than timed interrupts.
Timed interrupts have priority
over process interrupts via IB 0
or system interrupts. You can
change the priority with the
parameters in DX 0.
Data block DB 0
(block address list)
CPU 928B CPU 948
The block address list contains
the direct start addresses of the
blocks.
The block address list contains
the segment addresses of the
blocks. To obtain the start
address of a block, its segment
address must be shifted 4 bits to
the left.
Converting User Programs of the CPU 928B for the CPU 948
CPU 948 Programming Guide
1 - 20 C79000-G8576-C848-04

Siemens CPU 948 Specifications

General

Brand	Siemens
Model	CPU 948
Category	Controller
Language	English