Vaisala HMP110REF User Manual

Probe Grounding method
HMP60
HMP110
HMP110T
HMP110REF
There are two ways to ground the probe depending on installation type.
Choose only one of these methods:
• Grounding is provided by the metal cover of the probe. If using shielded
cables, shield is NOT connected to ground.
• A shielded cable is used, and the shield is connected to ground. In the
shielded cables supplied by Vaisala, the threaded connector connects the
shield to the probe housing.
When the probe is connected to a power supply, there is a delay as the probe
starts up and the analog output stabilizes. The delay depends on the output type,
and on the operating voltage that is supplied to the probe:
• Probes with analog output:
• 4 s at operating voltage 13.5 ... 16.5 VDC
• 2 s at other valid operating voltages
• Probes with digital output: 2 s
3.3.1 Wiring multiple digital devices
The maximum number of HMP60/HMP110 probes that you can connect to a system over the
RS-485 interface is 32 when the communication speed is 19200 bps or lower. Do not use
RS-485 termination with HMP60/HMP110 series probes.
Connecting other devices can decrease the maximum number of HMP60/HMP110
probes. If other devices require the use of termination, connect HMP60/HMP110
probes using an RS-485 repeater.
Chapter 3 – Installation
25

Vaisala HMP110REF Specifications

General

Brand	Vaisala
Model	HMP110REF
Category	Measuring Instruments
Language	English