Chapter 4 _________________________________________________________________ Operation
VAISALA ________________________________________________________________________ 31
CHAPTER 4
OPERATION
This chapter contains information that is needed to operate the HMP60
and HMP110 series probes.
Getting Started
NOTE
Before you connect an HMP60 or HMP110 series probe to a device, it is
recommended to power off the device.
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: 1 s
Serial Line Communication
NOTE
In analog probes, serial line communication is intended for service use
only.
HMP60 and HMP110 series probes support two-wire RS-485
communication. The RS-485 interface is non-isolated and offers a
maximum communications rate of 57600 bits/s.
There is no internal termination for the RS-485 on the probe. Use of
termination resistors is not recommended. If the resistors are used, the
possible increase in current consumption should be taken into account.
Connecting to the Serial Interface
The connection to the serial interface is via the 4-pin connector on the
probe: see Wiring on page 26.
