User Manual

E-M-HF4-V1_22

Rotronic AG

Bassersdorf, Switzerland

Document code

Unit

HygroFlex HF4 Humidity Temperature

Transmitters: User Guide

Instruction Manual

Document Type

Page

22 of 29

Document title

8 Maintenance

8.1 Service cable

IMPORTANT:

o Use service cable AC3009 with all 2-wire, loop powered transmitters. This cable powers up the

transmitter via the service connector. Do not use any other method for powering the transmitter when

using this cable AC3009 as this will create a ground loop and damage the transmitter. For the same

reasons do not use cable AC3006 with a 2-wire, loop powered transmitter.

o Use service cable AC3006 with all 3-wire transmitters as well as with digital models. This cable does

not provide power to the transmitter and the transmitter should powered separately when using this

cable

Both cables AC3006 and AC3009 convert UART (service connector) to USB and are used to connect the

transmitter to a USB port of a PC running the ROTRONIC HW4 software. Prior to using any of these

cables, the ROTRONIC USB driver must be installed on the PC. Both the driver and the installation

instructions (document E-M-HW4v3-Main) are located on the HW4 CD.

As an alternative, cable AC2001 is used to connect the HF4 to a probe input of the HP23 hand-held

calibrator. For service purposes, the HP23 offers essentially the same functionality as the HW4 software.

8.2 Location of the service connector (mini USB type)

WARNING: the service connector is a UART interface with a mini-USB connector type. Do not connect the

service connector directly to the USB port of a PC or hub.

The service connector can be accessed without opening the enclosure after removing the small red sealing

cover.

8.3 Periodic calibration check

Both the Pt 100 RTD temperature sensor and associated electronics are very stable and should not

require any calibration after the initial factory adjustment.

Long term stability of the ROTRONIC Hygromer humidity sensor is typically better than 1 %RH per year.

For maximum accuracy, calibration of the HF4 should be verified every 6 to 12 months. Applications

where the HF4 is exposed to significant pollution may require more frequent verifications.

HF32

Vertical mount: the service connector is

located either on the left side or on the

right side of the enclosure.

Horizontal mount: the service

connector is located at the bottom of

the enclosure (black arrow)