Intel MD566X manual DTE after receiving the +FTH=mod command

56K V.92 Data, Fax, and Voice Chipset

Table 5-3. Fax Mode Command Descriptions (Continued)

Note: An asterisk (*) denotes the factory-default setting.

Command Default Description

Transmit HDLC Data: The +FTH=<mod> command causes the modem to trans- mit data framed in HDLC protocol using the modulation mode selected. <mod> may have the values shown in Table 5-2 on page 74.

After receiving the +FTH command, the modem sends a “CONNECT” result code to the DTE. The modem then transmits signal converter training (if required) fol- lowed by flags until the first byte of data is sent by the DTE. The modem termi- nates the +FTH command upon detecting <DLE><ETX> characters in the data stream.

When the buffer is empty, the modem computes and appends the FCS (Frame Check Sequence) and a closing flag to the frame. The modem ensures that the minimum number of flags required by T.30 are sent before the data from the DTE begins to be transmitted.

The modem checks the final frame bit in the control field of each frame; this is the fifth-received bit of the second byte of each frame. If the final frame bit is a “1”, the modem ceases transmission after the frame is sent, returns to command state,

and sends the “OK” result code to the DTE. If the final frame bit is a “0”, the mo-

+FTH=n none dem sends another “CONNECT” result code to the DTE after the current frame is sent. The modem continues to transmit flags until the DTE takes one of the follow- ing actions:

•The DTE sends additional data. The modem then transmits another frame.

•The DTE sends only <DLE><ETX> (a null frame). The modem then turns off the transmit carrier and send the “OK” result code to the DTE.

•If the DTE transmits no additional data within 5 seconds from when the modem reported the “CONNECT” result code, the modem turns off the transmit carrier mode, returns to command mode, and sends the “ERROR” result code to the DTE.

In HDLC transmit mode, the modem performs HDLC transparency functions, FCS generation, and buffers the transmit data. The modem uses the configured meth- od of flow control to pause the DTE as necessary.

Note: If the modem is on-hook, it always returns an “ERROR” message to the

DTE after receiving the +FTH=<mod> command.

Range: <mod> = 3

Refer to Table 5-2 on page 74.

78 Intel Confidential Programmer’s Guide