Q0 - This makes sure that your modem sends response codes.

&C0 - This forces the carrier detect signal to always be on. geoFAX and the modem interface need this signal to be present.

&Q6 - This tells your modem to help buffer data.

&D2 - This forces the modem to hang up when geoFAX drops the DTR signal. This also disables the modem from auto-answering. geoFAX does not use the modem's auto-answer function but rather monitors the incoming ring itself.

&K4 - Pay close attention to this one. Many modems use this differently. This tells your modem to use XON/XOFF handshaking between geoFAX and your modem. It has nothing to do with any handshaking between your modem and the remote system. (RTS/CTS is not used, XON/XOFF is the default in faxing.)

NOTE: It's been found that some modems work better with RTS/CTS handshaking. The fax protocol states this is optional and at the modem manufacturer's discretion. You might want to experiment with using RTS/CTS if you the modem seems to hang up the phone line while sending faxes. The modem disconnecting the line appears to be the most noticeable problem when XON/XOFF is not working correctly. Most modems use &K3 for this setting, although your modem might be different.

&R1 - Informs the modem to always leave CTS on. Turbo232/Swiftlink won't allow any data to be sent if the CTS line is off.

If you are using a Class 2.0 modem, the init strings will be slightly different from the Class 2 strings since at the time of this writing, only the USRobotics modems were known to use Class 2.0 and the following changes are used.

&B1 - This keeps the serial port speed from affecting the data link speed.

&H2 - This is used in place of &K4 for XON/XOFF flow control.

&I2 - This is also used for XON/XOFF flow control.

BIT ORDER ADJUSTMENTS

Now we're getting technical! geoFAX sends/receives data to/from the modem and the modem in turn sends/receives data to/from the remote fax machine. geoFAX communicates with your modem with a byte of data at a time. Each byte is composed of 8 bits. The order in which those 8 bits are transferred is important. They can go with the low bit first or the high bit first. This same screen where you can edit your init strings also allows you to adjust the settings of the order of bits.

In most cases you will not need to change these and it is best to leave these settings alone. If geoFAX already works for you, making any changes to these settings will make geoFAX fail. If you are having trouble getting geoFAX to work, try different settings here but keep a note of the original settings so that you can put them back if you need to.

You can make different adjustments for sending and receiving. You can also make different adjustments as to how the bits are transferred between your modem and the remote system.

SERIAL PORT SPEEDS

geoFAX allows two different settings for the serial port speed. This is the bps rate that the Turbo232/Swiftlink will communicate at with your modem. It has nothing to do with the speed that will be used with the remote fax machine. Your modem and the remote fax machine will negotiate that setting on their own.