Accutech WI-BR-I-XP User Manual - page 21
Rev 1.56
15
Section 6: Configuring the Modbus Communications
6.3: Modbus Commands
The Base Radio responds to six Modbus commands including the Read
Holding Registers (03), Diagnostic (08), Get Com Event Count (11), Get
Com Event Log (12), Report Slave ID (17), and Read Device Identifica-
tion (43). The Read Holding Registers command provides the bulk of the
functionality with the remaining commands being used for diagnostics/
troubleshooting purposes. No other Modbus commands are supported and
will be responded to with an ILLEGAL FUNCTION exception (code 01).
A description of each command code is listed in the following sections.
6.3.1: Command 03-
Read Holding Registers
This command is used to read the contents of a contiguous block of hold-
ing registers in a Base Radio or Field Unit. If an invalid register address is
requested, an ILLEGAL DATA ADDRESS exception (code 02) will be
returned.
The following sections will break down the holding registers for the Base
Radio and Field Units, as well as how to understand the contents of the
registers.
6.3.1.1: Base Radio Holding
Registers
The following are the Base Radio holding registers for all mapping modes
(i.e. Device ID and Register mapping modes):
6.3.1.1.1: Base Radio Device Type
Registers
The Base Radio Device Type value is 255. This is the only possible value
for the Device Type holding registers for a Base Radio. Note that the reg-
ister is a 16-bit unsigned int for Base Radios.
6.3.1.1.2: Base Radio Device Status
Registers
Value
Base Radio Device Status
1 Base Radio Online
2+
Reserved For Future Use
Base Radio Holding Register (All
Mapping Modes)
Device ID:1 To 247 Max.
Register Address
Description
Register Type
00001
Device Type
16-Bit Unsigned Int
00002
Device Status
16-Bit Unsigned Int
00003
Number of Field Units Expected
16-Bit Unsigned Int
00004
Number of Field Units Communicating
16-Bit Unsigned Int
00005
Online/Offline Status Of Field Units 1-16
16-Bit Unsigned Int
00006
Online/Offline Status Of Field Units 17-32
16-Bit Unsigned Int
00007
Online/Offline Status Of Field Units 33-48
16-Bit Unsigned Int
00008
Online/Offline Status Of Field Units 49-50
16-Bit Unsigned Int
00009
Reserved For Future Use
16-Bit Unsigned Int
00010
Reserved For Future Use
16-Bit Unsigned Int
The following are the values for the Device Status holding registers.
These registers are bit field registers represented as a 16-bit unsigned int
for Base Radios.