Function Codes; Encapsulated Interface Transport / Read Device Identification - ABB FMBT-21 User Manual

48 Modbus/TCP – Communication protocol
Historically, Modbus client devices used 5-digit decimal addresses from 40001 to
49999 to represent Holding register addresses. 5-digit decimal addressing limited to
9999 the number of holding registers that could be addressed.
Modern Modbus client devices typically provide a means to access the full range of
65536 Modbus Holding registers. One of these methods is to use 6-digit decimal
addresses from 400001 to 465536. This manual uses 6-digit decimal addressing to
represent Modbus Holding register addresses.
Modbus client devices that are limited to 5-digit decimal addressing may still access
registers 400001 to 409999 by using 5-digit decimal addresses 40001 to 49999.
Registers 410000-465536 are inaccessible to these clients.

Function codes

The adapter module supports the Modbus function codes shown below.
Function code Name
03h Read Holding Registers
06h Write Single Register
10h Write Multiple Registers
17h Read/Write Multiple Registers
2Bh/0Eh Encapsulated Interface Trans-
port / Read Device Identifica-
tion
Encapsulated Interface Transport / Read Device
Identification
The adapter module supports the Modbus EIT/RDI objects shown below.
Object ID
00h Vendor Name
01h Product Code
02h Major/Minor Revision
03h Vendor URL
04h Product Name
Description
Reads the contents of a contiguous block of holding
registers in a server device.
Writes a single holding register in a server device.
Writes the contents of a contiguous block of hold-
ing registers in a server device.
Writes the contents of a contiguous block of hold-
ing registers in a server device, then reads the
contents of a contiguous block of holding registers
(same or different than those written) in a server
device.
Allows reading identification and other information
of the server.
Parameter "Read Device ID code" allows one to
define three access types:
• 01: Request to get the basic device identification
(stream access)
• 02: Request to get the regular device identifica-
tion (stream access)
• 04: Request to get one specific identification
object (individual access).
Name