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INX***DH-F199-B30-***INY***DH-F199-B30-***
MODBUS RTU Device Registers and Codes
4.4
Manufacturer-Specific Registers and Function Codes
The following paragraph describes the user-defined function codes 0x44h (write) and 0x45h
(read). User-defined function code 44h/45h is for less commonly used, off-line functions such
as setting serial port parameters and changing the device address. Some MODBUS hosts
cannot support this function code, but the frames can still be sent using a serial terminal
program on a PC that can send binary data on the serial port. Changes to the serial port
parameters and device address are stored in flash memory, so these settings are retained
when power is off. A soft power cycle (command AAh) or a manual power cycle is needed to
activate the new values.
Register Name
Baud Rate
Parity
Device Address
Activate Terminator
Read device HW version
Read device SW version
Restore to Factory Setting
Software Power cycle
Table 4.6
Example of Write Process
Set Device Address
Request (Command)
Name
Device Address
Function Code
Command
Number of Bytes
New Address
CRC
Table 4.7
Comma
Function
nd
Access
Code
20h
R/W
45h/44h 8 bits
21h
R/W
45h/44h 8 bits
22h
R/W
45h/44h 8 bits
23h
R/W
45h/44h 8 bits
30h
R
45h
31h
R
45h
55h
W
44h
AAh
W
44h
Value
7Fh
44h
22h
01h
05h
xxxxh
Data
type
Description and Values
Baud Rate values in Baud ( 0
= 2400 ; 1 =4800 ; 2 = 9600;
3 = 19200; 4 = 38400; 5 =
57600; 6 = 115200)
0: no parity
1: odd parity
2: even parity
Used to set the device
address; Valid range from 1
to 247
Used to set the internal
terminating resistor of 120
ohms
0 = inactive
1 = active
16 bits
HW version read as a BCD
value ( e.g.: 0110 means
1.10)
16 bits
SW version read as a BCD
value ( e.g.: 0110 means
1.10)
8 bits
No data ( command length
smaller)
8 bits
No data ( command length
smaller)
Response
Name
Device Address
Command
Command
Number of Bytes
CRC
Default
03h
02h
7Fh
(127d)
00h
Value
7Fh
44h
22h
01h
xxxxh
15
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