13
12
DISABLE SMS (DISABLE)
This input works as a digital input (see previous subsection)
and allows to ignore active errors and suspend SMS sending
during operations as start-up, maintenance, etc.
DIGITAL OUTPUT (DIG OUT)
This optoisolated terminal is an open collector output, which
can be used for external signaling through LED indicators or
small relays (see below diagram).
RS485 SERIAL PORT
HI504903
is also provided with a 2-pin RS485 terminal for
communication with Hanna
HI142
temperature dataloggers.
The RS485 standard is a digital transmission method that
allows long line connections. Its current loop system makes
this standard suitable for data transmission in noisy environ-
ments.
Specifications:
The RS485 standard is implemented in
HI504903
interface
with the following characteristic:
Data rate:
fixed to 1200 bps for communication with
HI142
temperature dataloggers
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 RS485 port of
HI504903
can connect up to 31
HI142
dataloggers on the same physical network, with a total line
length up to 1.2 Km using a 24 AWG cable.
For connecting the first
HI142
to the supervi-
sor, use a cable made as shown in the
“Appendix, section 1” and connect the A and
B wires to the A and B pins of the
HI504903
RS485 terminal.
INSTALLATION
RS232 AUXILIARY PORT
HI504903
is provided with an auxiliary RS232 port (D-Sub
9-pole female plug) for connection to a local PC using an
HI920010
Hanna cable.
Note
Use this RS232 auxiliary port
only
for local configuration of
the interface with
HI504903SW
software or local communi-
cation session with an instrument connected to the
HI504903
interface (see “Interface Configuration” and “PC Communi-
cation” sections for details).
Note
If the
HI920010
Hanna cable is too short for your applica-
tion, please refer to “Appendix, section 3” for details about
making a longer communication cable.
DIGITAL INPUT (DIG IN)
HI504903
is provided with a digital input, which can be
configured with
HI504903SW
software (see “Interface Con-
figuration” section) to send an alarm SMS when a DC voltage
from 5 to 30 V is applied or when it is disconnected.
This input can come from a relay contact or from an open
collector output (for example from a PLC).
Connect the positive pole of an external power supply to the
positive DIG-IN terminal; connect a command relay between
the negative pole of the external power supply and the nega-
tive DIG-IN (see also below diagram).
Note
Never connect mains or AC voltage supply directly to the
DIG-IN terminal.
Note
The digital input is optoisolated.
