C: ModbusIntelliBox-I/O 2100 User Guide 174Local SlaveThe IntelliBox itself hosts a local Modbus slave role. This local slave is addressable fromModbus/TCP at Unit Identifier 255 (0xFF).The local slave provides access to the relayand digital I/Os as a single data block:Address Name I/O0 XIO1 User configurable as input or output1 XIO2 User configurable as input or output2 Relay OutputThe server treats broadcast (Unit Identifier 0) as a request to forward to the Modbusserial port, but does not attempt to apply the function locally.The local slave supports the following Modbus functions:Number Name1 Read Coils2 Read Discrete Inputs3 Read Holding Registers4 Read Input Registers5 Write Single Coil6 Write Single Register15 Write Multiple Coils16 Write Multiple Registers23 Read/Write Multiple Registers43/14 Read Device Identification (Basic)Note: Any attempt to write to an XIO that the user has configured as an inputreturns exception 4 (slave device failure).
