Motorola V.3400 Operation Manual

Chapter 9

Fax Operation

GENERAL

The V.3400 can send and receive fax documents at speeds up to 14400
bps when used with the appropriate software. As a fax modem, the
modem conforms to EIA-578 which d efi nes a standard interface
between the DTE (a PC with fax software) and the DCE as a fax
mod em.

When used with a Class 1 fax software package, V.3400 is CCITT
Group 3 compatible and can send and re ce ive doc uments at 240 0, 4800,
7200, 9600, 12000, or 14400 bps with any Group 3 fax machine or PC
with a fax modem.

Service Class selection configures the modem for Class 0 data mode or
Class 1 fax mode. The LCD displa y indi cat es w hen fax mode is
enabled. The V.3400 default c onf iguration is for data mode; Service
Class is norm a ll y only chan g ed by the softw are as n ec essary.

Previous chapters i n this manual contain information about the modem
that should be understood prior to fax operation. Those chapters should
be read before this chapter.

Users shou ld underst an d the fax soft ware ma n ual before atte mpt ing fax
communications.

FAX OPERATION

The user's man ual for the Class 1 fax softwa re pa cka g e shoul d provi d e
most information necessary to configure the software and send and
rece iv e faxe s.

The info rm ati on in Chapt er 2 of this man ua l shou ld be consi d ered as
well, and also the next section of this chapter provides important infor­mation for proper fax communications.

V.3400 9-1

Fax Operation

MODEM I NIT IAL IZATION

For fa x operatio n, most fax software packages are equipped with a fax
initialization command string. Entering this command sets the active
profile for fax operation. In some cases certain options should be modi­fied for particular requi rements. The fa x sof twa re man u a l prov i des
infor mation about requirements.

FAX DEFAULTS

Factory def aul ts alon g with the ini tiali za tion com man d suppo rt f ax
operation. Some initialization comma nds include the default command
&F and will reissue it for each fax operation. Users must be aware that
some fax s oftwar e pac kag es do not incl ude the def aul t c omma nd or o nly
issue the default command when the fax software is first loaded. Subse­quent fax operat ion s may not reset the fax profile and if a fax require d
option has been change d by the user fax operati on wil l not work.

An example of a fax initialization command is AT&F V E S0=0

This can be interpreted as:

AT&F Reset the active profile to the factory default.

V Set response messa g es to dig it co de.

E Disable local echo (off).

S0=0 Disable autoa nsw er (off).

Fax Autoans wer

Some fax software takes control of autoanswer, disables autoanswer for
the modem, and answers the phone as internally programmed. Other
programs do not control autoanswer at all and require the modem to
have autoanswer enab le d. T he user mus t chec k t he s oftwa r e ma nua l fo r
the pa rticular req u irement s an d ref e r to Ch a pter 4 fo r m an u al /a u to a n­swer and TALK/DATA selection. Select the necessary options for f ax
operation.

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Fax Operat ion

FAX ASSOCIATED OPT IO NS

A number of options ca n be changed with out any effect on fax opera­tion. These inclu de items like speak er volum e and paus e for carrier.
Appendix E lists the AT commands and indicates how they may affect
fax operation. These commands can b e incorporated by personal prefer­ence in to the initialization command. The user shoul d compare fax
operation requirements with Appendix A and if necessary generate an
initialization command string compatible with the software and the
mod em.

Stored FAX Profile

Another a lternati ve is to develop a fa x initializat io n command and s tore
it in one of the user defined profiles. Fax initialization would include
the command that recalls that prof ile for fax operation. The user must
keep track of option changes between fax transmissions and if required
reset the fax profile for the next fax transmission .

CLASS 1 DETAILS

Operation as a f ax modem complies with EIA-578; details of Class 1
operation and compatibili ty are found in that standar d. There is no need
to be familiar with these details since they are handled by the Class 1
softw are packag e , but this sec tio n briefly sum ma riz es so me of them.

As a Servi ce Cl ass 1 fac si mi le DCE, the V. 3 400 provides th e basi c
servi ces required to support Group 3 facsimile operatio n. Support from
a Class 1 facsimi le DTE is require d to impleme nt the CCIT T T.30
recommendations for fax document transmission and the CCITT T.4
recommendations for encoding fax images. Using software control the
modem can

• connect calls

• generate messages

• detect waiting and silence

• transmit an d re ce ive data

• provide HDLC data framing, transparency, and error detectio n

The modem also filters data streams to and from the DTE in accordance
with the Class 1 specification.

V.3400 9-3

Fax Operation

The Class 1 standard assumes a serial asynchronous DTE-DCE connec­tion using EIA-232D (or CCITT V.24) circuits. EIA-232D circuits AB
(signal ground ), BA (transm itt ed data ), and BB (receiv ed data ) are
required for fax operation, while ad ditional circuits are optiona l. Refer
to Chapter 2 for hardware insta llation and EIA-232D data interf ace
information.

The mode m u ses inb a nd uni d ire ct ion al DC 1/ DC3 (XON/XOFF) flow
control to m atch the DTE-DCE data rate to the line signaling rate (hard­ware RTS /CTS i s opti onal) . S in ce 1200 b p s is t he min imum r at e need ed
to support T.30 Pha se C data transfer using V.29 9600 bps, a serial port
data rate of at least 19200 bps should be used with the modem. Since
flow control is used, this rate should not be changed during fax opera­ti on. T he mo dem d ete ct s t he DT E- D CE data r a te from t he AT c om mand
prefix as described in Chapter 5.

CLASS 1 COMMANDS

The commands in this section are normally issued by the fax software
and not by the user. They are prov ide d here for refe ren ce. While only
the lower order 7 bits of each ch aracter are used for command s and
parame ters, Ph ase C data transm ission or receptio n require s all 8 data
bits. Therefore, a data format which uses 8 data bits should be used for
fax mode.

Dial Command D

The di al command D, described in Chapte r 5, tells the modem to go off
hook, dial, a nd begin call origin ation. For fax oper ati on, s et the modem
for Service Class 1 operation before the dial command is issued; use the
+FCLASS=1 command.

The dial modifier, except R, can also be used in fa x mode. Dependi ng
on the X option selected, the modem will return the BUSY and NO
DIALTONE result codes as appropriate. If the modem is in the online
command state when a dial com mand is issued (e.g., a connection has
alread y been est abli sh ed), the mo de m returns an ERROR resu lt cod e.
The NO CARRIE R resu l t code ind ica te s that a connect ion could not be
established (no carrier detected) within the number of seconds specified
in status register S7, or the dial command has been aborted due to a
character sent from the DTE.

9-4 V.3400

Fax Operat ion

After dia ling the specifi ed num ber in fax mod e, the mo dem g enera tes
1100 Hz CNG tones in accordance with T.30 while trying to detect
either CE D (answ er back tone) or the HDL C pream ble of the first T.30
frame. The CNG tones ceas e a fter detecti ng ei ther of thes e two sign als.
To allow proper interaction with manually answered fax stations, detec­tion of CED is not required. After detect ing 1650 Hz (i.e., the HDLC
preambl e of the first frame), the modem enters V.21 Chann el 2 receive
state with HDLC framing and returns a CONNECT result code. This is
because dialing in fax mode (+FCLASS=1) implies an initial +FRH=3
command described later in this section.

Answer Com mand A

The A command instructs the modem to answer the call. For fax opera-
tion, set the modem for Service Class 1 operation before the A
comm and is issued; use the +FCLASS=1 command .

If the modem is in the online command state when an answer command
is issued (e.g., a connection is already established), modem returns an
ERROR resu l t cod e. Otherw ise, it answ ers the ca ll an d gene rate s a
2100 Hz CED (answer back) tone in accordance wit h T .30. The modem
then enters V.21 Cha nnel 2 transmi t state with HDL C framin g and
returns a CONNECT result code. This is because answering a call in
fax mode (+FCLASS=1) implies an in itial +FTH=3 command
described later in this section. In acc ordance with T .30, to allow proper
interaction with a m anually originated f ax call, the modem does not
require detection of CNG before generating CED or entering HDLC
transmit mode.

If the DTE sends a character while executing the answer command and
before CED is completed, the call is released and the modem will send
the NO CARRIER resul t code.

On Hook H

In fax mode, the H command instructs the modem to stop any transmis­sion and terminate the call by going on hook.

V.3400 9-5

Fax Operation

Off Hook H1

The H1 command instructs the mo dem to go off ho ok. In fax mode, thi s
migh t b e u s e d when t he u se r ha s us e d manual dialing to pla c e a f a x c al l.
In this case, no CNG ton es are generated and the in it i al +FRH=3 is n ot
implied; it must be explicitly issued by the software.

Class 0 Operation +FCLASS=0

Setting the Service Class to 0 with the +FCLASS=0 command sets the
modem in data mode. This default setting is normally only changed by
software if needed.

Class 1 Operation +FCLASS=1

Setting the Service Class to 1 with the +FCLASS=1 command c onf ig-
ures the modem as a Class 1 fax m odem. This command is normally
only issued by the fax software if needed. When set, the L CD displays
FAX CLASS 1 MODE .

Service Class Indication +FCLASS?

The cur rent Servi ce Class sett ing can be determ ine d with the
+FCLASS? command. A 0 response indicates the modem is configured
for data mode while a 1 indicates it is set f or fax mode. This informa­tion text is preceded and followed by <CR><LF> in addition to being
followed by an appropriate res ult code response.

Service Class Capabilities +FCLASS=?

The available Service Classes can be revealed by the +FCLASS=?
comma n d. The modem respon d s wit h the inf orm atio n text 0, 1
(preceded and followed by <CR> <LF>), indicating that the modem
suppo rts bot h data commu n icat ion and Class 1 fax ope rat io n.

Transmit Silence +FTS=

(Time)

The co mmand + FTS=(Time) causes the modem to wait in silence for
the specified amount of time and then send the OK result code to the
DTE. The (Time) value is in 10 ms increments from 0 to 2.55 seconds.
The mode m aborts the comma n d and send s an OK resul t code if the
DTE sen d s an ad dit io nal ch arac te r, which is disca rd ed , during the
command execution. This command returns an ERROR result code if
issued while the modem is on hook.

9-6 V.3400

Fax Operat ion

Receive Silenc e +FRS=

(Time

)

The command +FRS= causes the modem to listen for silence and report
back an OK resu l t code wh en the lin e has been silent for the speci fie d
amount of ti me. The (Time ) value is in 10 ms in crements from 0 t o 2.55
seconds.

The modem abo rts the comman d and send s an OK resul t code if the
DTE sends an additional character, which is discarded, during the
command execution. This command returns an ERROR result code if
issued while the modem is on hook.

Fax Transmit and Receive Modes

The fo l lo wi n g co m m an ds instruct the mo de m to tran s m it or re ceive
facsimil e dat a with t he desig n ate d modulation. Fl ow contr ol, dat a b uff­ering, and data filtering are used as appropriate, in accorda nce with the
Class 1 specification. Each of these com mands must be the last
command on the command line.

Command Description

+FTM=(MOD) Transmit da ta wi th ( MOD) carr ier
+FRM=(MOD) Receive data with (MOD) carrier
+F TH=(MOD) Transmit HDLC dat a wit h (MOD) carr ie r
+FRH=(MOD) Receive HDLC d ata with (MOD) carrier

The modem acce pts one of the values listed in Table 9-1.

Tabl e 9-1. Modulation Value s

Value Modulation Speed

3 V.2 1 c h annel 2 300 bps
24 V.27 ter 2400 bps
48 V.27 ter 4800 bps
72 V.29 7200 bps
73 V.17 7200 bps
74 V.17 7200 bps *
96 V.29 9600 bps
97 V.17 9600 bps

V.3400 9-7

Fax Operation

Tabl e 9-1. Mo dulat ion Values (Continued)

Value Modulation Speed

98 V.17 9600 bps *
121 V.17 12000 bps
122 V.17 12000 bps *
145 V.17 14400 bps
146 V.17 14400 bps*

* with short train

The V.3400 returns an ERROR resul t code if any of the above
commands are issued while the modem is on hook.

Facsimile Transmit +FT M=

(Mod)

+FTM= (Mod) ca us es th e modem to tr a ns mi t data using th e mo d ulation
and speed selected w ith the (Mod) param eter. For V.27 ter, V.29, and
V.17 modulations, the modem first transmits the required training
sequence (with echo protector tone). After it is appropriately configure d
for transmission, the mod em retu rn s the CONNECT resul t code and
transmits constant 1 bits until data is received from the DTE. For addi­tional info rmati on, consult the Class 1 specifica tio n.

Facsimile Receive +FRM=

(Mod)

+FRM= (Mod) causes the modem to receive data usin g the modulat ion
and speed selected w ith the (Mod) param eter. If the select ed carri er is
detected, a CONNEC T resu lt code is sent to the DTE; if a different
signal is detected, the modem sends a +FCERROR (CONNECT
ERROR) result code and returns to command mode. This command is
aborted i f the DTE sends any character to the modem other than DC1 or
DC3 during this mode. For additional information, consult the Class 1
specification.

HDLC Transmit +FT H=

(Mod)

+FTH=(Mo d) cau ses the mode m to tran smit HDLC framed data using
the modulation and speed selected with the (Mod) parameter. For V.27
ter, V.29, and V.17 modula tions , the modem will first tra nsmi t the
required training sequence (with echo protector to ne). Configured for
HDLC transmission, the modem transmits HDLC flags and returns the

9-8 V.3400

Fax Operat ion

CONNECT result code. H DLC flags will continue to be sent until the
first byt e of data is receiv ed from the DTE or un til 5 seco nds elaps es
with no data. For additional information, refer the Class 1 specification .

HDLC Receive +FRH=

(Mod)

Th e comm and +FRH= (Mod) causes the modem to receive HDLC
fram ed data using the mod ul ation and spee d selected with the (Mod)
parameter. If the selected carrier is detected, a CONNECT result code is
sent to the DTE; if a different signal is detected, the modem sends a
+FCERROR (CONNECT ERROR) result code and returns to command
mode. This command will be aborted if the DTE sends any character to
the modem other than DC1 or DC3 during this mode. For additional
inform ation , consu lt the Class 1 specifi ca tion .

x

Test Supported Range of Values +FT

=?, +FRx=?

The su pported rang e of val u es for an y of th e fax tran smit or rece iv e
comma nd s can be de termi ned wi th the +FTx=? or +FRx = ? command
where x is M, H, or S. The normal transmit and receive capabi lities are
interrogated with +FTM=? and +FRM=?, while the HDLC transm it
and recei ve ca pabil it ies are in terro g ated wit h +FTH=? and +FRH=?.
Since the modem can send and receive normal data or HDL C data at all
valid speeds up to 14400 bps, the modem returns the information text 3,
24, 48, 72, 73, 74, 96, 97, 98, 121, 122, 145, 146 for any of these four
commands if x is M or H. For the commands +FTS=? or + FRS=? the
modem returns the information text 0-255, indicating an allowed time
interval from 0 to 2.55 seconds. The appropria te informa tion text is
always preceded and followed by <CR><L F> and followed by an
appropriate result code response.

Class 1 Result Code +FCERROR

If the modem dete cts an y car rier or tone that differs from that spec ifi ed
in a +FRM or +FRH command, it sends the +FCERROR result code
an d r e t urns to comm and sta t e , allow i n g th e DTE to attempt a re covery.
The num eric form of thi s respo ns e is +F4.

V.3400 9-9

Fax Operation

Fax Auto Answ er +FAA=

The m odem can be set up to automatically detect if a fax or data call is
being answered. The command +FAA=1 enables this function and
+FAA=0 disable s it. This feature requi res spec ial sup port by the fax
software package.

Command Description

+ FAA=0 Disabl e fax auto an swer
+FAA=1 Enable fax auto ans wer

BINARY FILE TRANSFER

Some Class 1 software packages may provide an option for transferring
files between computers with fax m odems, using a Binary File Transfer
(BFT) standard. A lthough the received file is not a fax image, transmit­ting the file is similar to sending a fax. Since the modem allows T.30
error correction mode (w ith HDLC framin g up to 9600 bps), fax mode
can also be used for BFT if supporte d by the Class 1 soft ware pac k age.
The Binary File Transfer is an option in the fax software pack age, not a
separate mode of operation.

9-10 V.3400