Vaisala HMP110REF User Manual

4. Modbus communication
The Modbus variant used in HMP60 and HMP110 series probes is Modbus RTU. Modbus support
was added to HMP60 and HMP110 probes in 2016 for probe software version 2.1.4. The
following table lists the default communication settings used when Modbus is enabled at the
factory (chosen when ordering).
Table 7 Default Modbus communication settings
Description Default value
Serial bit rate 19200
Parity None
Number of data bits 8
Number of stop bits 2
Flow control None
Modbus device address 240
Serial delay 0
Communication mode Modbus RTU
Use Vaisala Insight software to change the Modbus serial communication settings if needed.
Download Vaisala Insight software at www.vaisala.com/insight.
The instrument must be switched o and on before the communication setting
changes take eect.
More information
‣
Accessing serial line command interface from analog or Modbus mode (page 36)
‣
Modbus reference (page 85)
4.1
Using multiple devices over RS-485
When you use HMP60/HMP110 series probes for Modbus communication over the RS-485
interface, the maximum number of HMP60/HMP110 probes that can be connected to a system
is 32 (with a communication speed of 19200 bps or lower).
RS-485 termination must not be used with HMP60/HMP110 series probes.
Chapter 4 – Modbus communication
29

Vaisala HMP110REF Specifications

General

Brand	Vaisala
Model	HMP110REF
Category	Measuring Instruments
Language	English