Shenzhen Hpmont Technology Co., Ltd Appendix B Communication Protocol
HD5L Series Controller User Manual -129-
Appendix B Communication Protocol
1. Peripherals Support
HD5L series controllers provide one RS485 communication interface which uses the standard
MODBUS communication protocol. By using the host computer (including communication
devices such as computer and PLC) the user can operate to read-write the controller’s function
code, read the state parameters and write the control command etc. The controller is in slave
mode when it is communicating.
2. Interfaces
Interface mode and pin definition
Communication mode
RS485 interface: asynchronous, semi-duplex.
Default: 8-N-2, 9600bps.
3. Network Mode
4. Protocol Format
The MODBUS protocol simultaneously supports RTU mode and ASCII mode, with corresponding
frame format as shown below:
Port pin
Port signal
RJ45
1
+5V
2
485+
3
+5V
4
GND
5
GND
6
GND
7
485-
8
Reserved
1 8
PC master
PLCmaster
RS232/RS485
switchingmodule
HD5L HD5L HD5L
Single-master and multi-slave
RS485
PC master
PLCmaster
RS232/RS485
switchingmodule
HD5L
Single-master and single-slave
RS485
HD5L
Slave
address
Frame head (at least
3.5 character spacing)
Function
code
Data
Checking
Modbus data frame
Frame tail (atleast
3.5 character spacing)
B