The following standard protocols are available on the CM 1241 communication modules:

• ASCII:
  For interfacing to third-party systems with simple transmission protocols, e.g. protocols with start and end characters or with block check characters. The interface handshake signals can be called and controlled via the user program.
• Modbus:
  For communication according to the Modbus protocol with RTU format:
  • Modbus master:
    Master-slave interfacing with SIMATIC S7 as master.
  • Modbus slave:
    Master-slave interfacing with SIMATIC S7 as slave; message frame traffic from slave to slave not possible.
• USS drive protocol:
  Instructions for connection of USS protocol drives are especially supported. In this case, drives exchange data over RS485. It is then possible to control these drives, and to read and write parameters.

Further drivers for downloading are also available.

Parameterization

Parameterization of the CM 1241 communication module is particularly user-friendly and simple with STEP 7 Basic:

• The user assigns the module characteristics via a parameterization environment integrated in STEP 7 Basic, e.g.:
  • the implemented protocol drivers that are used.
  • the driver-specific characteristics that are used.