Vaisala HPP272 User Manual

More Information
‣
Vaisala Insight Software (page 28)
‣
Configuration Registers (page 48)
5.4 Modbus
The probe can be accessed using the Modbus serial communication protocol. The supported
Modbus variant is Modbus RTU (Serial Modbus) over RS-485 interface.
More Information
‣
Modbus Reference (page 45)
‣
Setting Probe in Analog or Digital Mode (page 23)
5.5
Operation in Analog Mode
In analog output mode, the probe outputs the readings of two measurement parameters (one
parameter in each analog output channel). These measurement parameters are chosen at the
time of ordering the probe, and you can change them using Insight software and via Modbus.
You can check the chosen parameters in the calibration
certificate delivered with the probe.
The default output range for both channels is 4 ... 20 mA.
When using analog outputs, it is recommended to use a low supply voltage to minimize self-
heating and maximize measurement performance. The operating voltage range with analog
output is 15 ... 25 V.
When the probe performs the chemical purge, the analog outputs have a defined behavior:
• During start-up purge, analog output is in the error state (default: 3.6 mA).
• During interval purge and manually triggered purge, output is frozen to show the last
measured value before the purge began.
More Information
‣
Setting Probe in Analog or Digital Mode (page 23)
‣
Analog Output Error State (page 40)
‣
Configuration Registers (page 48)
‣
Chemical Purge (page 11)
5.5.1 Analog Output Overrange Behavior
If the values measured by the probe are outside the scaled analog output range, the analog
output goes in the error state. The default error state is 3.6 mA.
HPP272 User Guide M211972EN-B
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Vaisala HPP272 Specifications

General

Brand	Vaisala
Model	HPP272
Category	Measuring Instruments
Language	English