Michell Instruments HygroCal100, User Manual

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HygroCal100 User’s Manual
8 97500 Issue 3, January 2018
INSTALLATION
2.4.2 USB Communications Port
The USB type-B connector on the rear panel allows the HygroCal to be connected to
a PC, outputting the relative humidity and temperature values of both the reference
probes and the probes under test.
Figure 5 USB Communications Port
When connecting the port to a PC, the device will be installed as a virtual serial port,
and assigned its own COM port number, allowing communication with many different
engineering programs and programming languages.
The output will be in the following format:
InternalReferenceRH Probe1RH Probe2RH Probe3RH Probe4RH Probe5RH Probe6RH Probe7RH
InternalReferenceTP Probe1TP Probe2TP Probe3TP Probe4TP Probe5TP Probe6TP Probe7TP
0100 0114 FFFF 0115 FFFF FFFF FFFF FFFF 00E9 00E4 FFFF 00E3 FFFF FFFF FFFF FFFF
Each 2 byte hex word is a 16 bit unsigned integer, which should be divided by 10 to give
the actual decimal value of the associated reading.
e.g. Internal Reference RH value 0x0100 = 256. Dividing this value by 10 gives the
%RH value 25.6%
2.4.3 Service Access Port
The service access port has a cover which can be removed to access the HS3 control
sensor for replacement (see replacement instructions in Section 4.3).
The cover is held in place by two fl at-head screws.
Figure 6
Service Access Port