Modbus Protocol - LG ACHH017VBAB Installation And Owner's Manual

If the chiller enters the Modbus remote mode, all the information can only be monitored through the HMI. Actual operation control (start / stop or
changing the set temperature) can only be performed through the external controller. To control from the HMI, change the control mode to "Local".
Remote communication error CH10009 will occur when the communication is disconnected between the HMI and external controllers. When com-
munication is recovered, it will automatically resume. If the remote Modbus connection is not used, reset the power of the main PCB of the chiller to
cancel the alarm.
Modbus Interlock Protocol Details
The protocol details for Modbus interlock of external devices are:
• Physical layer: RS-485 serial line
• Mode: Modbus RTU mode
Figure 45: Applied Function Codes.
Function Code
0x01
0x02
0x03
0x04
0x05
0x06
0xF1~FF
See the Modbus protocols in the following pages.
• Baud rate: 9,600
• Parity: None parity
Sub-function
None
None
None
None
None
None
Reserved for Exception Code
Due to our policy of continuous product innovation, some specifications may change without notification.
©LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. "LG" is a registered trademark of LG Corp.

MODBUS PROTOCOL

• One (1) stop bit
• Applied function codes
Function Name
Read Coil Register
Read Discrete Input
Read Holding
Read Input
Write Single Coil
Write Single Holding
-
Start Address From Main Device
Address-1
Register Address-10001
Register Address-40001
Register Address-30001
Register Address-1
Register Address-40001
-
99