Siemens SIMATIC ET 200SP Manual page 16

Product overview
3.1 Characteristics of the CM AS-i Master ST
Use of the module
The CM AS-i Master ST module is a communication module for use in the
SIMATIC ET 200SP Distributed I/O System.
The CM AS-i Master ST features a 20 mm wide ET 200SP module housing. A BaseUnit (BU)
is required for use in the ET 200SP. The CM AS-i Master ST can be plugged into C0-type
BaseUnits (BU).
You can plug several CM AS-i Master ST modules into one SIMATIC ET 200SP station.
Each CM AS-i Master with firmware version V1.0 occupies 32 bytes of I/O address space.
From firmware version V1.1 onwards, the CM AS-i Master ST supports up to 288 bytes of
I/O address space. The number of possible AS-i master modules depends on the maximum
address space of the utilized Interface Module (IM) of the ET 200SP or the utilized
ET 200SP CPU.
In a SIMATIC ET 200SP station with an IM 155-6 PN ST standard interface module and a
maximum address space of 256 bytes, up to eight CM AS-i Master ST modules can be
plugged in (when the I/O address space is configured as 32 bytes).
Significantly more modules can be plugged into a SIMATIC ET 200SP station with High
Feature Interface Module IM 156-6 PN HF and a maximum address space of 1440 bytes.
If the ET 200SP contains other modules, the available address space is reduced and the
maximum number of AS-i master modules is reduced accordingly. The maximum number of
modules can be increased by shortening the I/O address space of the CM AS-i Master ST
module.
For further information, see the ET 200SP System Manual
(https://support.industry.siemens.com/cs/ww/en/view/84133942).
The CM AS-i Master ST module can generally be combined with all ET 200SP interface
modules. Any exceptions to this are documented in the delivery release product
announcement(s) of the interface module.
The CM AS-i Master ST module (Firmware V1.1 and higher) can generally be combined with
all ET 200SP CPU modules (Firmware V1.8 and higher). Any exceptions to this are
documented in the delivery release product announcement(s) for a CPU module.
The interface modules und CPU modules differ, among other things, in terms of the
maximum number of I/O modules, the length of the I/O process image in the station and the
length of the I/O process image for each I/O module. The technical specifications of the
interface modules and CPU modules can limit the selection of possible parameters of the
CM AS-i Master ST module. Note, in particular, that the length of the I/O process image of
the CM AS-i Master ST module must be selected in such a way that the maximum length of
the I/O process image of the interface module or CPU module is not exceeded.
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AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004