Page 44 of 55
King Pigeon Hi-Tech. Co., Ltd.
Ver 1.3
GSM/SMS/GPRS/3G/4G
Cellular IoT Gateway
Read Mapping
Register Qty
2
00 0AH
Read input register qty.
Receiver Return Data Format:
Content
Bytes
Data
(H: HEX)
Description
Transaction ID
2
00 00H
Identification of Modbus requests/responses
transactions
Protocol Identifier
2
00 00H
00 00: Modbus protocol
Data Length
2
00 17H
The length of subsequent data
Device Address
1
01H
01H Device, according to the data Master send
Function Code
1
03H
Read holding register
Range Data Bytes
1
14H
One address can read 2 bytes
Returning Data
20
00 14 00 1E 00
28 00 32 00 4B
00 41 00 0A 00
25 00 14 00 2AH
Returning Data
Example: Mapping address start from 20000, read 10 address data, then:
Server send:
00 00 00 00 00 06 01 03 4E 20 00 0A
00 00= Transaction ID; 00 00 = Protocol Identifier,00 00 stands for Modbus protocol; 00 06 = The length of
subsequent data; 01= Device address; 03= Read holding register ; 4E 20=Mapping register starting address,
current is Decimal data 20000; 00 0A = Read 10 register value;
Device answer:
00 00 00 00 00 17 01 03 14 00 14 00 1E 00 28 00 32 00 4B 00 41 00 0A 00 25 00 14 00 2A
00 00= Transaction ID; 00 00 = Protocol Identifier,00 00 stands for Modbus protocol; 00 17 = The length of
subsequent data;01= Device address; 03= Read holding register; 14= Returning 20 byte; 00 14 00 1E 00 28 00
32 00 4B 00 41 00 0A 00 25 00 14 00 2A = Returning data.
Register Mapping
Address
20000 20001 20002 20003 20004 20005 20006 20007 20008 20009
Value
00 14
00 1E
00 28
00 32
00 4B
00 41
00 0A
00 25
00 14
00 2A
8.5.4 Modify Data Type Mapping Address Data
If need to revise slave data which Ethernet connected, need to add slave in salve list of configurator. Write
command 16 for mapping, when mapping address value modified, will write to Ethernet matched slave
address.
If address 20000 mapping slave data type is Signed Int, sort AB.
Master Send Data Format:
Content
Bytes
Data
(H: HEX)
Description
Transaction ID
2
00 00H
Identification of Modbus requests/responses
transactions
Protocol Identifier
2
00 00H
00 00: Modbus protocol
Data Length
2
00 06H
The length of subsequent data