Introduction

You can use Modbus function code commands to perform diagnostics on the BMENUA0100 module. Modbus commands can reach the module only over its backplane port. Because Modbus is not an inherently secure protocol, you need to encapsulate Modbus commands within IPSEC.

Only FC FC43/14 (Read Device Identification) and FC03 (to read DDT MW%) requests are supported on the BMENUA0100 module.

Modbus Data Access and the Cybersecurity Operating Mode

The method you can use to access Modbus data depends on the cybersecurity operating mode. If the BMENUA0100 module is operating in:

• Standard mode: The BMENUA0100 module accepts the Modbus TCP/IP client data flow from any client that can access the backplane Ethernet network. Use standard Modbus communication methods, including DATA_EXCH, MBP_MSTR, READ_VAR and WRITE_VAR function blocks, and Control Expert commands.

• Secured mode: The BMENUA0100 module accepts the Modbus TCP/IP client data flow only from the M580 CPU. You can implement the DATA_EXCH block in the application.The READ_VAR and WRITE_VAR can also be used.

  NOTE: To address the Modbus server in the module, UnitID 100 needs to be used. Refer to your Modbus client documentation for information describing how to set this value. For example, when using the DATA_EXCH block, UnitId may be set with ADDMX as follows: ADDMX(0.0.3{192.168.10.2}100.TCP.MBS) where 192.168.168.10.2 is the backplane IP address of BMENUA0100 module.

43/14: Read Device Identification

The following device identification data can be returned using function code 43 / subcode 14: