Multi-Tech Systems 7500 User Manual

Page 290

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Cellular Phone Compatibility

ION 7500 / ION 7600 User’s Guide

Page 290

Modem AT Commands Technical Note

Description: This setup forces v.34 at maximum 4800 baud and forces error
correction. This also ensures other AT commands do not turn off error
correction and compression. The 4800 setting may be increased to 7200/9600,
but in most cases, using 4800 results in better throughput due to less errors for
the modems to deal with.

For the above application, the following are recommended modem initialization
string changes for the Multi-Tech modem (inside the ION meter):

AT command:

S10=100

Description: Increases disconnect time on loss of carrier

AT command:

B1

Description: If rate drops to 1200, use Bell protocol

For compatibility with the (older) Conexant internal modem:

Local modem: Black Box MiniModem 56k Data/Faxmodem, model MD1620A,
or Multi-Tech MultiModem, model MT5600ZDX

Necessary AT commands:

%E0-K1-SEC+1+MS=10,1,1200,9600

Description: This setup allows the modem to negotiate any baud rate between
1200 and 9600 bps. This setup also prevents v.34 connections by not allowing
the modem to negotiate anything higher than V32bis.

For the above application, the following are recommended modem initialization
string changes for the Conexant modem (inside the ION meter):

AT command:

%E0-K1-SEC+1+MS=10,1,120,9600

In addition, the modem site needs to be set up as follows, regardless of the actual
connection baud rate:

Modem Type: Black Box MiniModem 56k Data/Fax

Transmit Delay: 10 ms

Baud Rate: 9600 bps

RTS/CTS: unchecked

Receive Timeout: 5000 ms

Byte Timeout: 20 byte-time

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