Hanna Instruments HI 504901 - Manual (Page 8)

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POWER SUPPLY INPUT
Use a 12VDC adapter (HI710005 or
HI710006) and connect the black wire to
the positive input terminal (marked “+”) and
the black & white wire to the negative one
(marked “-”).
All hard wiring can be accomplished through five wa-
tertight cable glands on the bottom side of the case,
by passing wires through the rubber grommets and
tightening the nuts.
Note All connected cables should end with cable lugs.
BATTERY
FOR SAVING BATTERY, THE HI504901 IS SUP-
PLIED WITH BATTERY NOT CONNECTED.
PLUG THE BATTERY CONNECTOR BEFORE
STARTING OPERATION.
Use only rechargeable sealed lead-acid battery with
12 V and 0.8 Ah capability.
To substitute battery, please follow below instructions:
1. turn off the HI504901: turn OFF the power switch and
disconnect the interface from the mains;
2. remove the screws on the bottom of the two battery clips;
3. disconnect the battery cable from its connector;
4. substitute the old battery with a new one;
5. fix back the two girdles by tightening the screws;
Specifications:
The RS485 standard is implemented in HI504901 interface
with the following characteristic:
Data rate:
up to 9600 (selected while configuring the
interface through HI504901SW software)
Communication: bidirectional Half-Duplex
Line length: up to 1.2 Km typical, with 24 AWG cable
Loads: up to 32 typical
Internal termination: none
Connections:
The connections for the provided 2-pin RS485 terminal are
as shown on the below diagram.
The instrument has no internal line termination: to terminate
the line an external resistor equal to the characteristic line im-
pedance (typically 120
Ω ) must be added at both line ends.
HI504901 RS485 port can connect up to 32 instruments on
the same physical network, with a total line length up to 1.2
Km using a 24 AWG cable.
All the instruments connected to the RS485 port are “slave”
devices that are queried by the HI504901 supervisor. In
other words, the interface can work only as a “master” com-
ponent, whereas the connected instruments work as remote
terminal equipments answering to the commands only.
Each instrument (except the HI504901 interface itself) is iden-
tified by its Process ID number, included within the 00 to 99
interval, which corresponds to the Process ID configured
through the proper setup item (please refer to the instrument
instruction manual for a complete explanation).
Note If an instrument does not recognize the address within the
command string, then it discard all the following bytes.
As additional feature, the HI504901 interface is also pro-
vided with internal Fail Safe Open Line protection method.
To minimize electromagnetic interferences, it is recommended
to use shielded and twisted pair cable to connect the units.