The Modbus slave can be installed as a software module on every controller CPU. Controlled through a mapping table, it reads variables of the system and makes them available on Modbus registers, where they can be read by every standard-conformant Modbus master. Write accesses of the master are appropriately forwarded by the Modbus slave to the mapped variables. In this manner process variables of the user software, direct I/O signals, as well as system variables, such as time of the controller, can be transparently presented for the external Modbus master. 

All Ethernet ports for Modbus TCP and UDP, as well as all serial interfaces for Modbus ASCII and RTU, are available. These can also be distributed spatially to substations of the control system.



  • Supported protocols: 
    • Modbus TCP 
    • Modbus UDP 
    • Modbus ASCII
    • Modbus RTU
  • Use of the onboard interfaces of the CPUs
  • Possibility of spatial distribution of the interfaces via FASTBUS substations and EM213 or RS204 module
  • Mapping of any SVI variables in the Modbus Primary Tables
  • Mapping of any I/O channels in the Modbus Primary Tables


Modbus Slave

Modbus Slave EN
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Modbus Slave EN
Modbus Slave DE
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Modbus Slave DE

System overview