ROTRONIC HC2 - Manual (Page 12)

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 12 of 31
Document title
© 2009-2013; Rotronic AG E-M-HC2 Probes-V1_26
General description
3 General description
3.1 Power supply
The accuracy specified for the HC2 probes is valid only when the probe is supplied with a voltage within the
range of 3.3…5 VDC. The probes are tested and adjusted at the factory using a supply voltage of 3.3 VDC.
When a voltage source of 3.3…5 VDC is not available, the probe should be used together with a voltage adapter
(see separate document E-M-HC2-accessories) so as to provide 3.3…5 VDC to the probe. Use of a voltage
adapter allows powering the probe from a voltage source of 5 to 24 VDC or 5 to 16 VAC.
During start-up the typical current consumption of the probe is initially 8 mA during 2ms and 5 mA during the
next 2s. Without a power supply limiter, the start-up current may reach a maximum of 50 mA. After start-up the
current consumption is on average less than 3 mA. Randomly distributed current spikes of maximum 1 mA
during 2μs are normal during operation and are caused by the probe micro-processor and associated
components.
The HC2 probes are polarity protected by a keyed connector. There is no electrical polarity protection.
3.2 Measured parameters
The HC2 probe measures relative humidity with a ROTRONIC Hygromer ® IN1 capacitive sensor and
temperature with a Pt100 RTD.
3.3 Calculated parameters
Using the ROTRONIC HW4 software, the HC2 probe can be configured by the user to calculate either the dew
point or the frost point.
3.4 Analog output signals
The HC2 probe features two 0…1 V linear analog output signals. The default factory settings are as follows:
Output 1: 0…1 V (humidity)
= 0…100 %RH
Output 2: 0…1 V (temperature) = -40…60˚C
Using the ROTRONIC HW4 software any output signal can be made to correspond one of the following:
 Relative humidity
 Temperature
 Dew or frost point
The scale of each analog output can be set within the numerical limits of -999.99 and 9999.99.
If so desired, any output can also be disabled (no signal).
The D/A converters used to generate the analog output signals feature a 16-bit resolution. The 0…1 V analog
output signals exhibit a small positive offset of 3 mV or less at 0 V.
Minimum load requirements apply to the external device or circuit connected to the probe voltage outputs. These
requirements are defined in the “Operation” chapter
Note: users who require an analog signal other than 0…1 V should either contact ROTRONIC or connect the
probe to one of the available transmitters.