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
‣
‣
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)
‣
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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