Intermec VT220/ANSI, Programmer'S Reference Manual

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SECTION 9
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Extended Commands
VT220/ANSI Terminal Emulation Programmer’s Reference Guide 9-11
Transmit Only On RS-232 Port (#P)
The Transmit Only On RS-232 Port extended command lets
the wireless station send information to a slaved RS-232
device, such as a printer or bar code printer. The command
uses the RS-232 communications port to send data to the
device. The wireless station checks data from the host com-
puter for a transmit sequence, then sends the requested da-
ta. The host computer signals the wireless station for a
transmit command by inserting the characters “#P” into the
display at Line 1, Columns 2 and 3. Characteristics of the
transmission immediately follow the #P command.
When constructing a Transmit Only command, the data to
be sent should be placed at Line 2, Column 1. The data
must be less than 1840 bytes in length (after “=yy” com-
pression). The last character must be “#.” The wireless sta-
tion sends the data to the RS-232 port until it detects a “#”
character. Due to possible system fragmentation of a data
stream, the “#” in Line 1, Column 2 should be the last char-
acter placed on the screen. This will assure that all data is
present before the extended command is parsed (removed).
Control characters sequences for mnemonics APC (applica-
tion program command) and ST (string terminator) can also
start and end data. The last data character must be a “#”
(pound sign). The wireless station sends the data to the
RS-232 port until it detects a “#” character and the string
terminator sequence.
The output stream takes the form of ASCII characters. For
nondisplayable ASCII characters, you may insert the char-
acters “=yy,” where “yy” is the hexadecimal representation
of the output byte.
Table 9-2 lists columns in which characters must appear.