Siemens 6GK7542-1AX00-0XE0 CM 1542 RS-422/485 Communication Module

The Siemens 6GK7542-1AX00-0XE0 is a communication module (CM) for the S7-1500 PLC family. It provides a single RS-422/485 serial interface, enabling the controller to communicate with a wide range of serial devices such as drives, barcode scanners, weigh scales, and third-party controllers using point-to-point or multi-point networks.

Interface Specifications

• Physical interface: 1x RS-422 / RS-485 (electrically isolated)

• Connector type: 9-pin D-sub female (with screw lock)

• Transmission rate: 300 baud to 115.2 kbps (RS-485) / 38.4 kbps (RS-422)

• Supported protocols: Freeport (ASCII), Modbus RTU master/slave, 3964(R), USS

• Cable length: Up to 1200m (RS-485), up to 100m (RS-422)

• Termination: Switchable internal termination resistors

Protocol Support

The module can be configured for various protocols via TIA Portal. For Modbus RTU, it supports function codes 01,02,03,04,05,06,15,16. As a freeport, any user-defined frame format (7 or 8 data bits, parity, 1 or 2 stop bits) is possible. The module also handles RS-485 half-duplex automatically.

Diagnostics and Configuration

Configuration is done in STEP 7 (TIA Portal) using the Hardware Catalog. Parameters include baud rate, data format, protocol selection, and timing parameters. The module provides diagnostic LEDs: RUN, ERROR, and RX/TX activity. Detailed diagnostic information is available via the CPU's diagnostic buffer.

Electrical Isolation and Protection

All serial signals are galvanically isolated from the backplane bus (1500 Vrms). The module includes transient voltage suppression (TVS diodes) on the RS-485 lines to protect against ESD and surges up to ±15 kV. The D-sub connector shell is connected to protective earth.

Mechanical Data

Dimensions: 35mm width x 130mm height x 100mm depth. Weight: 200g. Mounting: The module snaps onto the S7-1500 mounting rail and connects via the U-shaped backplane bus connector. It occupies one slot in the I/O rack.

Environmental Limits

Operating temperature: 0°C to 60°C horizontally mounted, 0°C to 50°C vertically. Storage: -40°C to 70°C. Humidity: 10-95% non-condensing. Vibration: 2g (10-150 Hz). Shock: 15g, 11ms half-sine.

Certifications

CE, UL, cUL, EAC, KC, and RCM certified. RoHS compliant. Suitable for use in Zone 2 hazardous locations (ATEX/IECEx) when installed in appropriate enclosure.

Typical Applications

The 6GK7542-1AX00-0XE0 is used to connect S7-1500 controllers to legacy serial devices, retrofit existing Modbus RTU networks, or interface with barcode readers and RFID systems.

Ordering and Accessories

Order number: 6GK7542-1AX00-0XE0. Required accessories: a suitable 9-pin D-sub cable (e.g., 6ES7902-3AB00-0AA0 for RS-485). The module includes a D-sub connector shell but does not include the connector body.

Conclusion

The Siemens 6GK7542-1AX00-0XE0 CM 1542 provides a robust and flexible serial communication solution for S7-1500, enabling easy integration of RS-422/485 devices into modern automation architectures.