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King Pigeon Hi-Tech. Co., Ltd.
Ver 1.3
GSM/SMS/GPRS/3G/4G
Cellular IoT Gateway
Device Address
1
01H
01H Device, Range: 1-247, according to setting address
Function Code
1
06H
Write single holding register, function code 06
Mapping Register
Address
2
4E 20H
Address range: 4E 20H-50 1CH. Mapping data type
address range, refer to
Address”]
at manual bottom.
Write Data
2
00 64H
Data writing value is Decimal data 100
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 06H
The length of subsequent data
Device Address
1
01H
01H Device, according to the data Master send
Function Code
1
06H
Write single holding register
Mapping Register
Address
2
4E 20H
Address range: 4E20H-501CH, mapping data
type address range.
Write Data
2
00 64H
Write 100 successfully
Example: If address 20000 mapping slave data type is Signed Int, sort AB, modify mapping address 20000
register to 100, then:
Server send:
00 00 00 00 00 06 01 06 4E 20 00 64
00 00= Transaction ID; 00 00 = Protocol Identifier,00 00 stands for Modbus protocol; 00 06 = The length of
subsequent data; 01= Device address; 06= Modify single holding register value; 4E 20=Modify address 20000
register value; 00 64 = Write Decimal value 100;
Device answer:
00 00 00 00 00 06 01 06 4E 20 00 64
00 00= Transaction ID; 00 00 = Protocol Identifier,00 00 stands for Modbus protocol; 00 06 = The length of
subsequent data; 01= Device address; 06= Modify single holding register value; 4E 20= R Modify address
20000 register value; 00 64= Modify to Decimal value 100.
If need to modify multiple data type mapping address, pls check function code 16 in Modbus protocol.
8.6 Transparent Transmission DTU Application
Device can support data transparent transmission: DTU function. Could server transmit data to device via
GPRS/3G/4G, device will transfer the data to RS485 port directly without deal with. Once device receive data
from RS485, also transmit to cloud server directly via GPRS/3G/4G. When device RS485 port no need mapping
slave, or connect to others which is not standard Modbus RTU protocol, then can choose transparent
transmission as below:
(1) Items connect to device via RS485, set RS485 port parameter;
(2) Basic setting page to set device ID;
