8
Modbus Protocol (Modbus/TCP)
Protocol structure
94
Manual – Fieldbus Interface DFE33B EtherNet/IP and Modbus/TCP
8.2.5 Service FC43 – Read Device Identification
The service FC43 Read Device Identification is also referred to as MEI ("Modbus Encap-
sulated Interface Transport"). It can tunnel services and method calls. The service Read
Device Identification is tunneled with the MEI type 0x0E. In accordance with Modbus
specifications, there are 3 blocks (Basic, Regular and Extended) that can be read. The
DFE33B option supports the Basic and Regular blocks (conformity level 02). The entire
block is always read (streaming). This means that values 01 and 02 are permitted in the
Read Device ID Code. The Object ID must be zero. The response is not fragmented.
Example Request:
Response:
Exception:
Byte Designation Meaning / permitted values
0 - 6 MBAP header See section "Header"
7 Function code Required service: 43 (Read Device Identification)
8 MEI type 0x0E
9 Read device ID code 01 or 02
10 Object ID 0
Byte Designation Meaning / permitted values
0 - 6 MBAP header See section "Header"
7 Function code Service: 43 (Read Device Identification)
8 MEI type 0x0E
9 Read device ID code 01 or 02
10 Conformity level 02
11 More follows 0
12 Next object ID 0
13 Number of objects e. g. 3
14 Object ID
15 Object length
16 Object value
17 ....
Byte Designation Meaning
0 - 6 MBAP header See section "Header"
7 Function code 43
hex
8 Exception code Fault code
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