53
4 Communication
Alpha Technologies
The initialization string (Item #527) is a set of commands the CFR sends to the
modem to initialize it. For a US Robotics modem, the string is:
•
ATX4Q0V1&H0&R1&I0&B1
Where:
•
X4:
Extended set of result codes.
•
Q0:
Result codes are displayed.
•
V1:
Display verbal (words not numbers) result codes.
•
&H0:
Disable transmit data flow control (neither hardware “CTS” nor software
“Xon/Xoff” flow control).
•
&R1:
Disable hardware receive data flow control (set modem to ignore RTS
and send data all the time).
•
&I0:
Disable software data flow control (no “Xon/Xoff” flow control).
•
&B1:
Set the RS–232 serial port rate to fixed (set modem to detect the AT
command baud rate and maintain it).
The first three commands are supported by all Hayes-compatible modems. The last four
are supported by US Robotics and some other manufacturers.
TIP:
Do not include the auto answer command in the initalization string. The CFR
sends an AT command to control the auto answer mode (either “ATS0=1” or
“ATS0=0”).
For modems that do not support the extended Hayes commands, you should create an
equivalent command. In most cases the simplified string:
•
ATQ0V1
works well.
4.7 Installing and Using the External Modem (Continued)
