ROTRONIC HF8 - Manual (Page 8)

E-M-HF8-V2_10
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroFlex HF8 Humidity Temperature
Transmitter: User Guide Instruction Manual
Document Type
Page 8 of 35
Document title
© 2012; Rotronic AG E-M-HF8-V2_10
3.8.2 RS-485 serial interface
The RS-485 interface can be used to connect together up to 64 devices in a multi-dropped arrangement. In
principle, an unlimited number of such networks can be monitored with the HW4 software, but each RS-485
multi-drop network is limited to 64 devices.
A master device is required to connect a RS-485 network to a PC, such as for example:
o HF8 transmitter with both an Ethernet and a RS-485 port.
o Cable AC3010 (master substitute) with USB and RS-485 ports.
RS-485 Compatibility:
The HF8 uses the RO-ASCII communications protocol. This protocol is not compatible with the protocol used
by the previous generation of ROTRONIC instruments and by the HygroLog HL-NT data logger. Do not
connect legacy products or the HL-NT data logger to the same RS-485 multi-drop network as the HF8
transmitter.
3.8.3 Relay contacts
The HF8 is available with up to 4 relay contacts (SPDT: single pole double throw). Connection to a PC running
the ROTRONIC HW4 software is required to configure each relay contact.
Each relay contact can be associated with any of the two HF8 probe inputs and can be made to monitor alarm
conditions associated with one of the following:
o Relative humidity or parameter measured by an analog 1-channel probe
o Temperature
o Calculated parameter, including a Custom Calculation (if enabled)
A relay output is energized when the value of the parameter being monitored corresponds to a user defined
out-of-limits value. High and low limits for the measured and calculated parameters can be defined for each
individual probe input with the HW4 software Device Manager (see E-M-HW4v3-F2-015).
The HW4 software is also used to configure the operating parameters of each relay such as time delay to
energize or de-energize the relay, latching or non-latching operation and can also be used to limit operation of
the relays to a time schedule.
3.9 Optional display and keypad
The optional LC display option of the HF8 has a backlight which can be set
to be either permanently on, or to be on for a few seconds when a key is
pressed on the keypad. The backlight can also be disabled.
The display shows data from one probe at a time. When both probe inputs
of the HF8 are being used, the difference between the two probes can also
be displayed (Delta Probe).
The data from one probe or the difference between two probes or up to two
user defined Custom Calculations can be shown on the display. Selection
of the displayed data is done from the keypad (+ or – key).