Fax Modem (250-3581) Fax Class 2 Operation Faxback Doc. # 5883 5.1 COMMAND SYNTAX AND GUIDELINE 5.1.1 DTE COMMANDS The ISO 646 character set (T.50 International Alphabet 5, American Standard Code for Information Interchange) is used for issuance of commands and responses. Only the low-order 7 bits of each character are used for commands or parameters; the high order bit is ignored. Upper case characters are equivalent to lower case characters. For Phase C data transmission or reception, all 8 bits are needed. DTE COMMAND LINES A command line is a string of characters sent from a DTE to the DCE while the DCE is in a command state. Command lines have a prefix, a body, and a terminator. The prefix consists of the ASCII characters "AT" (065, 084) or "at" (097 116). The body is a string of commands restricted to printable ASCII characters, (032-126). Space characters (ASCII 032) and control characters other than CR (ASCII 013) and BS (ASCII 010) in the command string are ignored. The default terminator is the ASCII character. Characters that precede the AT prefix are ignored. BASIC COMMAND SYNTAX Characters within the command line are parsed as commands with associated parameter values. The basic commands consist of single ASCII characters, or single characters preceded by a prefix character (e.g. "&"), followed by a decimal parameter. Missing decimal parameters are evaluated as 0. EXTENDED COMMAND SYNTAX The facsimile commands are use extended syntax. They are preceded by the "+F" characters. and they are terminated by the semicolon ";" character (ASCII 059) or by the that terminated the command line. AT+FAE=0; +FCR 1 This command instructs the DCE to answer automatically a data or fax call and also enables reception. AT+FCLASS=0 for Data Mode. AT+FCLASS=1 For service Class 1 Fax. AT=FCLASS=2 for Service Class 2 Fax. In Class 2, the DCE makes and terminates calls, manages the communication session and negotiates (T.30 protocol) and transports the image data to DTE. The T.4 protocol management of image data, etc. is done by DTE. The response to: AT+FCLASS=0 in Data Mode or AT+FCLASS=2 in Service Class 2 Fax is OK The service class may be set by the DTE from the choices available using the "+FCLASS+" command. GENERAL RULES 1. +Fnnn commands must be entered completely otherwise an ERROR response is sent. 2. All response messages are preceded and followed by . Multiple response commands, e.g, +FDIS; +FCSI: and +FDCS: will therefore appear to have a blank line between them. 3. Fax Class 2 commands can be separated by the ":" character. The ":" can be omitted if desired. Note that non-data commands cannot be separated by ":" which is allowed by a dial modifier. 4. All Class 2 commands are assumed to be the final command on a command line. Additional characters will be ignored. 5. An ERROR message will be generated if any of the following conditions: A. A Class 1 command is received while in Class 2. B. A Class 2 command is received while in Class 1. C. A Class 1 or Class 2 action command is received while in data FAX Modem mode. D. A Class 2 read-only parameter is given the "=" form of a +F command (e.g., AT+FAXERR+5). E. A Class 2 action command is given the inappropriate "=" or "=?" form (e.g., AT+FDR= ?). 5.1.2 SERIAL PORT SPEED AND FLOW CONTROLS During fax mode, the DTE-DCE port speed is 19200 bps. The DCE provides a speed buffer of 1024 bytes and provides DC1/DC32 (XON/OFF) or RTS/CTS method of controlling the data into the buffer. This flow control is controlled by AT&K3 or AT&K4 command. This method of data flow control is available only for DTE to DCE direction of data. There is no provision of data flow control from DCE to DTE. DATA STREAM TERMINATION The DCE exchanges streams of data with the DTE while executing data transfer command. The ASCII character(016) is used as a special character, to shield special characters. The character pair (<106><003>) is used to mark the end of a stream. The following patterns are used: any data ... end of stream any data. single in data any data... delete DTE TO DCE STREAMS The DCE filters the data stream from the DTE. And removes all character pairs beginning with . The DCE recognizes as the stream terminator. The DCE recognizes and reinserts a single in its place. The DTE filter stream data to the DTE. And insert extra characters ahead of data. DCE to DTE Streams The DTE must filter the data stream from the DCE, and removes all character pairs beginning with . The DTE recognizes as the stream terminator. The DTE must recognize and reinserts a single in its place. The DCE filter stream data to the DTE, and insert extra characters ahead of data. 5.1.3 AUTO ANSWER The DCE can answer as a dat DCE or as a fax DCE. It can answer the call adaptively, i.e, it can determine whether call is 'data'or 'fax'. The +FAE parameter controls this feature. AT+FAE=1 :Auto answer as a facsimile or, :A data FAX Modem depending on call. CONNECT xxxx :DCE status response if data call +FCON :DCE status response if fax call 5.1.4 IDENTIFICATION OF T.30 OPTIONS Group 3 devices negotiate session parameters in DIS, DCS and DTC frames. There parameters are defined in Table 5-2. 5.1.5 SESSION STATUS REPORTING The DCE provides reports to the DTE on the status of a session. The DCE provides following status reports: 1. Connection and hang up status: +FCON +FHNG:<0-255> 2. Requested DIS session parameters +FDIS: reports remote facsimile capabilities. Syntax : +FDIS: VR, BR,WD,LN,DF,EC,BF,ST 3. +FDCS: reports the negotiated parameters 4. Phase C prompts: XON, XOFF,DC2 5. Phase C base status reports : depending upon copy quality and related end-of-page status. +FPTS : <1-5> 5.1.6 PROCEDURE INTERRUPT NEGOTIATION CCITT allows a station to request a procedure interruption at the end of a page. This request is passed between stations by the PIP, PIN and PRI-Q messages. 5.2 SERVICE CLASS 2 IDENTIFICATION AND SELECTION The fax Class 2 commands are summarized in Table 5-1. Three commands report identification and selection information. Each of these three commands cause the DCE to send a message to the DTE. The messages reside in EPROM starting at ROM address 2000h (ROM bank 3 address 6000h) and can be modified by the OEM. Each message is 20 bytes (ASCII encoded) followed by the terminating character (binary 0). If any message is modified, the firmware checksum must be recalculated and stored at address ROM address 6000h (ROM bank 0 address 6000h). 5.2.1 +FMFR?, REQUEST MANUFACTURER IDENTIFICATION The +FMFR? command cause the DCE to send a message identifying the DCE product manufacturer. The message starts at address 2000h. The binary terminator is located at address 2014h. 5.2.2 +FMDL?, IDENTIFY PRODUCT MODEL The +FMDL? Command cause the DCE to send a message identifying the DCE product model. the message starts at address 2015h. The binary terminator is located at address 2029h. 5.2.3 +FREV?, IDENTIFY PRODUCT REVISION The +FREV? command causes the DCE to send a message identifying the DCE product model revision number. The message starts at address 202Ah in EPORM. The binary terminator is located at address 203Eh. 5.3 SERVICE CLASS 2 ACTION COMMANDS These commands transfer data, and punctuate session. They also release specific T.30 message. All action commands must be the last command on a command line. This is indicated by terminating . All action commands initiate processes. The FAX Modem will not accept other commands from the DTE until the FAX Modem issues a final result code (e.g., OK, CONNECT). The FAX Modem will abort the process if it receives any character before the final result code is issued. TABLE 5-1. FAX CLASS 2 COMMANDS COMMAND FUNCTION SERVICE CLASS ID +FCLASS= Service Class Class 2 Action Commands D Originate a Call A Answer a Call +FDT= Data Transmission +FET=N Transmit Page Punctuation +FDR Begin or Continue Phase C receive Data +FK Session Termination CLASS 2 DCE RESPONSES =FCON Facsimile Connection Response +FDCS: Report Current Session +FDIS: Report Remote Identification +FCFR Indicate Confirmation to Receive +FTSI: Report the Transmit Station ID +FCSI: Report the Called Station ID +FPTS: Page Transfer Status +FET: Post Page Message Response +FHNG Call Termination with Status CLASS 2 SESSION PARAMETERS +FMFR? Identify Manufacturer +FMDL? Identify Model +FREV? Identify Revision +FDCC= DCE Capabilities Parameters +FDIS= Current Sessions Parameters +FDCS= Current Sessions Results +FLID= Local ID String +FCR Capability Receive +FPTS= Page Transfer Status +FCR Capability to Receive +FAA Adaptive Answer +FBUF? Buffer Size (Read Only) +FPHCTO Phase C Time out +FAXERR Fax Error Value +FBOR Phase C Data Bit Order 5.3.1 ATD, ORIGINATE A CALL Syntax: ATD.... The DCE can support a DTE command to originate a call using the ATD command. If this command is unsuccessful, the DCE reports an appropriate failure or error type result code such as NO CARRIER, NO DIALTONE or BUSY. If this call is successful, the typical DCE response is: ATDnn...nn (go off-hook, dial; get CED) +FCON DCE detects flags)] [+FCSI:] +FDCS: OK The DCE dials detects calls in progress and generates the CNG tone. Then it waits for a DIS frame. On detection of the first Phase B preamble (V.21 ch.2 modulated by 300 bit/s HDLC flags) it reports the "+FCON" message to the DTE. The DCE then switches to 19.2K bps. The DCE generates a DCS frame based on the received DIS frame and on the previously set +FDIS parameter. A +FDT command from the DTE releases the DCE to transmit that DCS frame. The DCE repots the initial received T.30 negotiation messages, including the DIS frame and the optional CSI ID string. The +FDIS: report is followed by the OK final result code. Continued on Faxback Document # 5884 (SMC-04/07/94)