USRobotics V.34 user manual Courier High Speed Modems

COURIER HIGH SPEED MODEMS

&B2 Fixed for ARQ calls/Variable for non-ARQ calls. Answer mode only. When the modem goes off hook and connects in ARQ mode, it shifts its serial port rate up to a user-specified rate, for example, 38.4K bps. If the connection is not under error control, the modem behaves as if it were set to &B0 and switches its serial port rate to match the connection rate of each call.

To implement this feature, first set your software to the desired rate. Then send the modem the AT &B2 [other settings] &W command.

The modem stores the rate of the command in NVRAM along with the settings. Each time it makes an ARQ connection, the modem checks NVRAM for the specified serial port rate.

When sending subsequent configurations to NVRAM, be sure your software is set to your selected serial port rate, so that the correct rate is maintained.

&Nn Connection rate variable or fixed.

&N0 Variable rates. Default. The Courier negotiates with the remote modem for the highest possible connection rate, depending on the capabilities of the remote modem. This is the recommended setting, and is required for the Courier V.32 terbo to connect at 21.6K bps. Both modems must be U.S. Robotics modems with V.32 terbo to make a 21.6K bps connection.

&N1- Fixed rate. The modem only connects if the remote &N14 modem is operating at the same rate. If not, the modem

hangs up. If you wish, you can filter out calls at other than a specific rate, for security or other reasons, by fixing the connection rate.

The connection rate must always be lower than, or equal to, the serial port rate, never higher.

4-22 Data Mode Operations