http://www4.ad.siemens.de/WW/news/en/8803744
Expanding the S7-22x CPU
This entry is available in the following languages:


Entry ID: 8803744
Date: 12/09/2003




QUESTION:
Are there are limitations in terms of how you can expand the S7-22x CPU with expansion modules?

ANSWER:
Expansion modules can be added to S7-22x CPUs except for the CPU S7-221. If more onboard I/O signals are required in the system, the CPU's onboard I/Os can be expanded by means of additional digital and analog inputs and outputs. There are also various function modules available for the expansion.
The S7-222 CPU can support up to two expansion modules. This is restricted by resources within the CPU. Up to 7 expansion modules can be added to 224 / 226 and 226 XM-type CPUs, regardless of the type of expansion module.

Important:
Only one connecting cable may be used for expansion modules (6ES7 290-6AA20-0XA0) in order to create a multi-line setup.
If you are using a CP 243-2 PLC-interface module, bear in mind that this module occupies two slots.
The maximum number of expansion modules that can be extended depends on the CPU's power balance. Each S7-200 CPU supplies a DC voltage of 5V and 24V DC. The CPU has a 24V DC encoder power supply that delivers a 24V DC to the integrated inputs and to the relay inputs on the expansion modules. If the power requirements for the CPU exceed the internal voltage supply capacity, you can also connect an external 24V DC supply to the inputs and the relay inputs on the expansion modules.
The CPU also has a 5V DC voltage source for the connected expansion modules. If the power requirements of the expansion modules exceed the voltage supply capacity, some of the expansion modules will have to be dispensed with to enable the CPU's energy balance to be complied with.

Note:
If you require further information on how the power balance is calculated and on the performance capability supplied by the CPU, as well as information about the hardware setup and about the technical data for the expansion modules, refer to the system manual for the S7-22x which you can find in Entry ID: 1109582.

Keywords:
System limitations, Hardware configuration