Siemens S5-135U/155U appendix Cpu

CPUs, Memory Cards, Memory Submodules, Interface Submodules

5.2CPU 948

This section contains the hardware description and the technical specifications of the CPU 948.

Details on programming the CPU 948 can be found in the CPU 948

Programming Guide.

5.2.1Technical Description

This section contains information on the application, design and structure of the CPU 948.

Application	You can use the CPU 948 in single and multiprocessor operation in the
	S5-135U/155U central controller (see Chapter 6).
	There are two versions of CPU 948:
	S The CPU 948-1 offers 640 Kbytes of internal user memory (RAM).
	S The CPU 948-2 offers 1664 Kbytes of internal user memory (RAM).
	A SIMATIC S5 flash EPROM memory card (known as a memory card for
	short in the following) can be inserted in the CPU 948 as the storage medium
	for user program and user data. The contents of the memory card are copied
	into the internal RAM of the CPU upon overall reset.
	The programming language is STEP 5 (LAD, CSF, STL, SCL). The CPU 948
	processes all STEP 5 operations at very high speed, and uses fast
	floating-point arithmetic.
	The following program processing levels are possible:
	S	Cyclic
	S Time-controlled (9 different timebases, real-time controlled, timeout)
	S Interrupt-driven from the S5 bus (8 process interrupts at block boundaries
		via IB0 or, alternatively, 4 system interrupts)
	S	Soft STOP.
Design	The electronic circuitry of the CPU 948, including the RAM, is on two PCBs
	of double Eurocard format which are screwed to each other. The two PCBs
	must not be separated. The front plate width of the module is 2 2/3 standard
	plug-in stations, i.e. 40 mm. In the central controller rack, the CPU 948
	occupies two slots.

System Manual	5-17
C79000-G8576-C199-06