User Guide

79
MODEM CONNECTION
A modem connection can be established between HI 504
and a remote computer over a telephone line. The connec-
tion with a standard modem allows the user to ask the
controller from a remote position about its status, measure-
ments and to change some parameters, while for receiving
alarm indications it is necessary to install the HI 504900
GSM module.
Setup item O.31 (“Modem calls answer enable”) must be set
to “On”.
When using the Hanna HI 504900 cellular module, it has to
be enabled by setting P.00 to “CELL” (in addition to O.31 set to
“On”); when using a standard modem, set P.00 to “PC”.
A SIM card able to receive data calls must be used.
Many devices can be monitored through a remote modem
connection, simply connecting all the devices and the mo-
dem (or Hanna cellular module) to the same RS485 network.
Only one device has to be configured through O.31 to an-
swer to modem calls. That device will be the one controlling
the modem (or cellular module). To avoid conflicts, the fol-
lowing must never be done:
• put more than one modem or GSM 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 HI 504);