Epson Multi-mode Data Controller MFJ-1278B - Manual (Page 127)

MFJ-1278B MULTI-MODE ADVANCED OPERATION
The display characteristics of the MFJ-1278B are also modified in Transparent Mode. Data
is sent to the computer exactly as it is received over the radio, including all 8 bits of each byte
received. Features such as auto-linefeed insertion and screen wrap are disabled, and echoing
of input characters is disabled. The parameters that control these features in Command Mode
and Converse Mode are not changed by entering Transparent Mode, and all display features
are re-enabled when the MFJ-1278B is returned to Command Mode. Most of the link status
messages that appear as the MFJ-1278B moves between disconnected and connected states
are also disabled in Transparent Mode.
In order to permit the Command Mode entry character to be transmitted freely in Transparent
Mode, the escape to Command Mode from Transparent Mode has been made a little more
complicated. You can still return to Command mode by transmitting a BREAK signal, just as
in Converse Mode. You can also utilize the Command Mode entry character in the following
way.
You must wait for a time period after typing the last character to be sent. This time is set by
the command CMDTIME. Following this wait, you must type three Command Mode entry
characters (default <CTRL-C>) within an interval CMDTIME of each other. After a final
CMDTIME interval in which no characters are typed, you will see the
cmd:
prompt. If any characters are typed during this interval (even Command Mode entry
characters) the escape will be aborted and all the Command Mode entry characters that have
been typed will be sent as packet data. If you set CMDTIME to zero you will not be able to
escape from Transparent Mode using this second procedure.
FLOW CONTROL
Whenever data is transferred to computers (home computers or TNCs), there is a chance that
the data will be received faster than the computer can handle it. Some programs try to deal
with this by providing data buffers for storing incoming data until the program is ready for it.
However, this merely postpones the problem, since there is a limited amount of room in any
buffer. In order to prevent loss of data the computer must be able to make whatever is
sending data stop sending, and later tell it to resume sending. If you are a home computer
user, you are probably already familiar with one type of flow control, which allows you to
stop the output from the computer while you read it and restart it when you are ready for
more.
Data lossThe MFJ-1278B's input buffer may fill up in Command Mode if you try to type too
long a command. In Converse Mode the buffer may fill up for any of several reasons: you
may be using a faster serial port baud rate than the radio data rate; radio data transmission