80
The modem connection (both with
HI504900
and
HI504902
) allows the user to ask the controller from a re-
mote position about its status, measurements and to change
some parameters, while for receiving alarm indications it is
necessary to install the
HI504900
cellular module .
Many devices can be monitored through a remote modem
connection, simply connecting all the devices and the mo-
dem or cellular module to the same RS485 network .
Only one device has to be configured through O .31 to
answer to modem calls . That device will be the one control-
ling the modem or the cellular module . To avoid conflicts,
the following must never be done:
• put more than one modem or cellular module in the same
RS485 network;
• set O .31 to “On” in more than one device in the same
RS485 network;
• set P .00 to “CELL” in more than one device in the same
RS485 network (SMSs can not be sent from more than
one
HI504
);
• set O .31 to “On” in one device and P .00 to “CELL” in
another one within the same RS485 network;
• put a PC monitor within the RS485 network .
Provided the above, any Hanna instrument with RS485 port
can be attached to the network and monitored remotely .
