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MFJ-1278B MULTI-MODE BASIC OPERATION
The number of graphics characters, "nnn", following a FAX frame header, depends on the
FAXMODE. See horizontal density under the FAXMODE command for more information.
Multi-level FAX Picture Raw Data Format
In FAX mode the MFJ-1278B can provide data thru the RS-232 port in raw data format.
With special terminal software which can support this data format, you can display and save
multi-gray levels pictures. The number of gray levels which the raw data format provides
thru the RS-232 port is determined by the command TVBREAK. Current TVBREAK is set
to 16 levels of gray.
To invoke multi-level FAX receiving, under the cmd: prompt, type:
MULTIFAX ON <ENTER>
then, make sure that you are in the FAX mode by typing:
MODE FX <ENTER>
Type K to enter CONVERSE mode, then type L to start receiving raw FAX data. Note that
with MULTIFAX turned On, you must type L to start receiving data. Unlike the 2 level
format which the MFJ-1278B firmware detects the beginning of a FAX picture and also
signal the end of the FAX picture, in multi-level FAX the terminal program will establish
synchronization and decide when to start and when to finish printing picture to the screen.
Note that when MULTIFAX is turned ON, the PRINTGRA command will be ignored. This
means that in FAX mode and with MULTIFAX turned ON, MFJ-1278B will start to send
raw data to the terminal regardless of the setting of PRINTGRA command.
For those who wishes to write program to support this multi- level raw data format, the
following information will be useful to you:
Upon typing the L character, MFJ-1278B will start to send the raw-data stream. Terminal
program should look for the distinctive sync pattern at this time to detect the beginning of the
picture. Raw-data stream will continue to be sent thru the RS-232 port until the end of
picture pattern is detected or a "CTRL-C" is received. Therefore for multi-level FAX the
terminal program is responsible for attaining synchronization to begin a picture and to detect
the end-of-picture to stop printing.
In 8-gray levels raw multi-level data are packed two pixels- per-byte. To enable ASCII
transparancy of the raw data, the MFJ-1278B biases each byte with +30H. On transmit, you
must likewise bias the outgoing data with 30H.
There are two exceptions. If the actual data byte, before unbiasing, is p or q, then the 1200
Hz Syne tone is being received. A "
p
" means it was received in the first time position, a "
q
"