Siemens 6ES7241-1CA50-0XB0 SIMATIC S7-1200 CB 1241 RS485 Communication Board

The Siemens 6ES7241-1CA50-0XB0 SIMATIC S7-1200 CB 1241 is a communication board that adds one RS 485 interface to a compact CPU, supporting Freeport, ASCII, Modbus RTU master/device, and USS protocols at up to 250 kbit/s. It draws 75 mA from the backplane bus and connects over point-to-point cable runs up to 1000 m.

Technical Specifications

Certifications & Standards

• CE
• UL
• cULus
• RCM
• KC

Selection Notes

The CB 1241 plugs into the S7-1200 CPU's onboard communication board slot rather than a rack expansion position, adding RS 485 connectivity without using up a signal-module slot. In Modbus RTU master mode the CPU can poll up to 247 slave devices under standard Modbus addressing, with a maximum of 32 devices per physical segment before a repeater is required; Modbus RTU device mode instead lets another master poll this CPU. The USS protocol, available as a library function, is the relevant mode when the RS 485 link talks to Siemens drives rather than third-party Modbus instruments.

Applications

Adds RS 485 serial connectivity to an S7-1200 for Modbus RTU instrument networks, USS-based drive control loops, or Freeport ASCII communication with third-party serial devices.