ROTRONIC HC2 - Manual (Page 20)

E-M-HC2 Probes-V1_26
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroClip 2 (HC2) Humidity Temperature
Probes: User Guide
Instruction Manual
Document Type
Page 20 of 31
Document title
© 2009-2013; Rotronic AG E-M-HC2 Probes-V1_26
Lightning protection
Cabling in areas with a risk of lightning requires a lightning protection. For cabling underground in between
buildings, we recommend the use of special fiber optic cables. If this is not possible, use copper cables that
are suitable for underground installation.
6.2 Analog signal wiring
Preferably use a shielded cable to connect the analog outputs of the HC2 to other devices. The maximum
cable length is determined by the maximum error that the user will accept. This can be calculated as follows:
Error (V) = cable resistance x current through load
6.3 Minimum analog output load
The HC2 analog outputs are short circuit tolerant and have an internal resistance of less than 10 Ω
For proper operation, the minimum external load of each output should be at least 1000 Ω.
6.4 Digital signal wiring
Use one of the available connecting cables (see Accessories) to connect the UART digital interface of the
HC2 probe to other devices. Without a signal booster, the maximum cable length should not exceed 5 m
(16 ft).
6.5 Grounding
In the case of a fixed installation, ground the HC2 probe, especially if the electronics will be subjected to a low
humidity environment (35 %RH or less). The power supply and digital ground (GND) and the analog ground
(AGND) should be tied separately to a proper ground so as to avoid spikes in the analog signals.
7 Operation
7.1 Operation with an indicator, data logger or transmitter
The HC2 probes are compatible with a large number of indicators, data loggers and transmitters from
ROTRONIC. Operating instructions are provided in each device manual.
7.2 Stand-alone operation as an analog probe
The HC2 probes can be used as a conventional analog probe. See Accessories, supply voltage adapters,
connectors and cables. Use the HW4 software to configure the probe as desired, complete the mechanical
and electrical installation and power up the probe.