User Guide

47
MODEM CONNECTION
A modem connection can be established between the HI
504910 transmitter and a remote computer over a telephone
line. Setup item O.31 (“Modem calls answer enable”) must
be set to “On”.
A standard modem connected to the HI 504910 transmitter
through an RS232 to RS485 adapter, or the Hanna GSM
module HI 504900 (with a SIM card able to receive
data calls) can 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 cellular module in the same
RS485 network;
• set O.31 to “On” in more than one device in 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.
The modem (or cellular module) must be configured (only
once while setting up the network) through a PC with an
RS232 terminal program (as HyperTerminal) or Hanna HI
92500 application software (“Options” menu : “Configure
modem”). The string to be sent to the modem for configuring
it is “AT&F0V1&D0&C0&S0X3E0&K0&Y0&W0<CR>”, while
“AT&F0V1&D0&C0&S0X3E0\Q0&Y0&W0<CR>” must be
used for the Hanna cellular module (<CR> = Carriage
Return). In case the above command causes an error in the
modem answer, then it has to be divided into smaller pieces:
“AT&F0<CR>”, “ATV1<CR>”, “AT&D0<CR>”,
“AT&C0<CR>”, “AT&S0<CR>”, “ATX3<CR>”,
“ATE0<CR>”, “AT&K0<CR>” (or “AT\Q0<CR>” for the
cellular module), “AT&Y0<CR>”, “AT&W0<CR>”. This is
needed because if during processing of AT commands in the
same line one of them leads to an error, the following com-
mands are not processed. After slicing the configuration string