The CM 1243‑2 communication module is the AS-Interface master for the SIMATIC S7‑1200 and has the following features:

• As many as 62 AS-Interface slaves can be connected
• Integrated analog value transmission
• Supports all AS-Interface master functions in accordance with the AS-Interface specification V3.0
• Indication of the operating state on the front of the device displayed via LED
• Display of operating mode, AS-Interface voltage faults, configuration faults and peripheral faults via LED behind the front panel
• Compact enclosure in the design of the SIMATIC S7‑1200
• Suitable for AS-i Power24V: In combination with the optional DCM 1271 data decoupling module, a standard 24 V power supply unit can be used
• Configuration and diagnostics via the TIA Portal

Design

The CM 1243‑2 communication module is positioned to the left of the S7‑1200 CPU and linked to the S7‑1200 via lateral contacts.

It has:

• Terminals for two AS-i cables (internally jumpered) via two screw terminals each
• One terminal for connection to the functional ground
• LEDs for indication of the operating state and fault statuses of the connected slaves

The screw terminals (included in scope of supply) can be removed to facilitate installation.

Function

The CM 1243‑2 supports all specified functions of the AS‑Interface Specification V3.0.

The values of the digital AS‑i slaves can be activated via the process image of the S7‑1200. During configuration of the slaves in the TIA Portal, the values of the analog AS‑i slaves can also be accessed directly in the process image.

It is also possible to exchange all data of the AS-i master and the connected AS-i slaves with the S7‑1200 via the data record interface.

Changeover of the operating mode, automatic application of the slave configuration and the re‑addressing of a connected AS‑i slave can be implemented via the control panel of the CM 1243‑2 in the TIA Portal.

The optional DCM 1271 data decoupling unit (see "Accessories ordering data") has an integrated detection unit for detecting ground faults on the AS-Interface cable. The integrated overload protection also disconnects the AS‑Interface cable if the drive current required exceeds 4 A. For more information on DCM 1271, see "Power supplies and data decoupling units" в†’ "Data decoupling units for S7‑1200".

Notes on safety

In order to protect plants, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art industrial security concept. Siemens products and solutions only represent one component of such a concept.

For more information on the topic of Industrial Security, see http://www.siemens.com/industrialsecurity.

Configuration

To configure CM 1243‑2, you require STEP 7 V11 + SP2 or higher.

For STEP 7 V11 + SP2 or higher, the additional Hardware Support Package for CM 1243‑2 is required. This is available from the Industry Online Support Portal. See https://support.industry.siemens.com/cs/ww/en/view/72341852.

The software enables user-friendly configuration and diagnostics of the AS-i master and any connected slaves.

Alternatively, you can also apply the AS-Interface ACTUAL configuration at the "touch of a button" via the control panel integrated in the TIA Portal/STEP 7.

When operated on a S7‑1200 CPU with firmware version V4.0 or higher, the firmware version V1.1 (or higher) is required for the CM 1243‑2.