Instruction manual

Page 21
Local Echo
- Local echo of modem commands must be set to off (E0).
On/Off Hook Control
- The external modem is initialized to on hook (H0).
Modem Result Messages
- Configure the modem to respond with AT command result
messages (Q0 ).
Format of Result Messages
- Configure the modem to respond with text rather than numeric
result messages (V1).
Carrier Detection
- Configure the modem to control the carrier detect RS-232 signal line based
on the presence of the carrier signal (&C1 ).
Data Terminal Ready
- When using the DB-9 terminated communications cable, configure the
modem to go to go on hook and assume the command mode when DTR is toggled (&D2). If the
RJ-11 communications cable is used, configure the modem to override the DTR state (&D0)
because this cable does not support the DTR signal line.
The default setting for the initialization string is E0H0Q0V1&C1&D2. This should be changed for
cases where the modem in question does not support the default commands. In these cases, the
equivalent command for the modem of interest should be substituted.
For external modems
that support error control it is necessary to disable the error control. The AT command to
disable error control should be appended to the initialization string. For external
modems that support data compression and flow control it is necessary to disable both
data compression and flow control. The AT commands to disable data compression and
flow control may be appended to either the initialization string or the Call Answering and
Call Origination Strings. See table 6 for recommendations.
Call Answering Strings
The kV RSX contains two 20 byte strings which can be programmed to accept AT commands
which pertain to configuring the external modem to answer incoming calls. These are initially set
to all spaces.
Call Origination Strings
There are four 20 byte strings which can be programmed to accept AT commands which pertain
to configuring the external modem to originate outbound calls. These are initially set to all
spaces.
CAUTION
: The following modem options should NEVER be placed in any meter
modem setup string as you may prevent successful communication with the
meter:
E1, H1, Q1
& commands: &Sn, &Tn, &Vn, &Wn, &Yn, and &Zn
S-registers: s3, s4, s5, s14, s16, s21, s23, s24, and s27
Dial modifiers: s=<n>
Baud Rate
The rate that the kV RSX communicates with the external modem (DTE rate) is configured
through programming of the Answer Baud Rate and the Originate Baud Rate in the kV RSX
AMRA tables. The initial baud rate used to setup the external modem is the Answer Baud Rate,
which is set to 9600 bps at the factory. The Originate Baud Rate also defaults to 9600 bps.
Unless the external modem operates at speeds slower than 9600 bps, these values should
remain at there initial settings. When using slower speed modems it is necessary to reprogram
the Answer and Originate Baud rates to the speed of the modem. For slower DTE speeds it is
necessary to put E0 in the modem reset string following the modem reset command(s).