E-m-hf4-v1_22 – ROTRONIC HF4 User Manual

Page 18

E-M-HF4-V1_22

Rotronic AG
Bassersdorf, Switzerland

Document code

Unit

HygroFlex HF4 Humidity Temperature
Transmitters: User Guide

Instruction Manual

Document Type

Page 18 of 29

Document title

Measuring humidity or temperature only

Operation of the HF43 does not require both current loops to be closed. When using the HF43 to measure
either humidity only or temperature only, close only the loop that is being used.

Using the ROTRONIC HW4 software, any unused output of the HF43 can be disabled.

6.4.3

HF45: digital output

Connectors and terminal block diagram

Notes:

Terminal K1-3: this terminal (protective or earth ground) is not tied with GND. If so desired, K1-3 can be tied
with GND by closing a solder pad on the PCB

Terminal block K3 (RS-485): pins K3-1 and K3-2 can be used to power all instruments on a RS-485 multi-
drop from a single external 15 VDC power supply with adequate mA rating. In this case, do not use terminals
K3-1 and pin K1-2 (normally used to power the HF45).

WARNING: Connecting a device to an active Ethernet network can disrupt communications on the network.
Before connecting the HF4, make sure that it is properly configured for your network

6.4.4

Grounding (all models)

We generally recommend grounding the (-) side of the power supply, especially if the electronics will be
subjected to a low humidity environment (35 %RH or less).

Terminals

Description

K1-1: GND

Power supply (-) or neutral
(tied with other GND)

K1-2: V+

Power supply: 5…40 VDC (+)
or 12…28 VAC (Phase)

K1-3: -

►

Protective ground (see note below)

K3-4: D-

RS-485 Bi-directional
TX- / RX -

K3-3: D+

RS-485 Bi-directional
TX+ / RX +

K3-2: GND

Ground / Power supply (-)

K3-1: PWR

DC (+) 15…40 VDC (+)
(optional, see note below)