This procedure is used to initialize a GVC 14400 Modem. The first procedure is for enabling the modem for dialin, and the second is to set the modem up for dial out. There are not many differences, but they are important.

Enabling a modem for dialin under CDOS:

The following commands (less their comments) need to be sent to the modem. The easiest way to do this would be to set the port as an AUX port and use ADUMB to initialize the modem. Set handshaking to none for this exercise. Don't forget to use the AUX command with the correct AUX port the modem is connected to. COM1 is AUX0, COM2 is AUX1, and the first Addon Port is AUX2. You should see an OK after hitting return for each command as an indicator that the modem understood the command.

AT&F        (Reset the modem to it's factory defaults)

ATS0=1    (Answer on first ring)

AT&C1      (DCD tracks carrier)

AT&D3      (When DTR drops, drop carrier, reset modem)

AT&S1      (DSR on only during connect)

AT\Q3        (RTS/CTS flow control)

ATQ1         (Quiet mode)

ATE0         (Turn off command echoing)

AT&W0     (Store current settings in NVRAM)

Once you have configured the modem don't forget to enable RTS and CTS handshaking for the port, as that is what we set the modem up for.

Configuring a modem for dialout

The following commands(less their comments) need to be sent to the modem. The easiest way to do this would be to set the port as an AUX port and use ADUMB to initialize the modem. Set handshaking to none for this exercise. Don't forget to use the AUX command to use the correct AUX port the modem is connected to. COM1 is AUX0, COM2 is AUX1, and the first Addon Port is AUX2. You should see an OK after hitting return for each command as an indicator that the modem understood the command.

AT&F        (Reset the modem to it's factory defaults)

ATS0=0    (Do not answer phone)

AT&C1     (DCD tracks carrier)

AT&D3     (When DTR drops, drop carrier, reset modem)

AT&S1      (DSR on only during connect)

ATE0         (Turn off command echoing. At this time, you will no longer see the characters being echoed back)

AT&W0     (Store current settings in NVRAM)

Once you have configured the modem don't forget to enable RTS and CTS handshaking for the port, as that is what we set the modem up for.