Vaisala HMD60 Series - Modbus and BACnet Communication; Modbus and BACnet Overview

5. Modbus and BACnet Communication
5.1 Modbus and BACnet Overview
HMD65 can be accessed with the Modbus and BACnet protocols over the RS-485 interface.
The protocol selection and communication settings for either protocol are entered with the
DIP switches on the HMD65 component board (see Figure 18 (page 26)).
3
2
1
7
4 5 6
Figure 18 Modbus and BACnet DIP Switches and Screw Terminals on HMD65 Component Board
1
DIP switch for setting RS-485 termination (120 Ω resistor) ON/OFF
2 Screw terminals for RS-485 (Modbus/BACnet) communication
3 Screw terminals for power supply input wiring (15 … 35 VDC / 16 … 24 VAC)
4 DIP switches for setting the device MAC address: see Figure 19 (page 27)
5 DIP switches for setting the communication bitrate (4800 … 115200 bps) and parity (N/E)
6 DIP switch for selecting either Modbus RTU or BACnet MS/TP mode
7 LED indicators for RS-485 transmit/receive activity
Modbus
The Modbus variant used in HMD65 is Modbus RTU. For a list of the Modbus registers available
in HMD65, see Modbus Registers (page 48).
HMD65 User Guide M212243EN-A
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