Fieldbus Interface DFE33B EtherNet/IP and Modbus/TCP

Modbus Protocol (Modbus/TCP)

Introduction

I

8.1.2

Services (function codes)

For process data exchange, parameter data exchange and unit identification, the

DFE33B option provides four service FCs (Function Codes).

• FC 3 Read Holding Registers

• FC16 Write Multiple Registers

• FC23 Read/Write Multiple Registers

• FC43 Read Device Identification

The FC3 and FC16 services allow reading or writing of one or more registers. FC23 allows a register block to be read and written simultaneously. You can identify a unit with service FC43 by reading out the identity parameter.

8.1.3

Access

The implemented registers and possible services (function codes) for data exchange are summarized in the following table.

Offset (hex) Read

0 – 3 –

4 – FF Process input data (actual values)

Meaning for

Write

–

Process output data

(setpoints)

100 – 103

104 – 1FF

–

Process output data (setpoints)

–

–

200 – 2FF Result acyclic parameter channel

300 – FFFF –

Special case: 219E

(8606 dec

)

Fieldbus timeout interval, read value

Request acyclic parameter channel

–

Fieldbus timeout interval, write value

Access

–

FC3,

FC16,

FC23

Comment

Reserved

• DFE33B: 0 – 10 words

• DFE33B gateway. 3 – 24 words (in steps of 3)

Reserved –

FC3 Used by clients other than the controlling client for reading the setpoints

4 words FC3,

FC16,

FC23

– Reserved

FC3, FC16 Parameter P819: 16 bit value, timeout interval in ms

8

Manual – Fieldbus Interface DFE33B EtherNet/IP and Modbus/TCP

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