ECHO Command The ECHO command prompts the printer to return a
specified message to the host computer. Use the ECHO
command to synchronize the printer with the host computer
to ensure that the status received is the requested status
information.
Syntax: @PJL ECHO [<words>] [<CR>]<LF>
Response Syntax: @PJL ECHO [<words>] <CR><LF>
<FF>
Parameters:
<words> — The <words> parameter must begin with a
printable character, and can contain any Roman-8
character from 33 through 255, in addition to space
characters and horizontal tabs. The <words> parameter
is not a string variable, and therefore need not be
enclosed in quotation marks. The parameter should be
unique, such as the time indicated by the real time clock
at the moment the ECHO command is issued. A unique
message eliminates the possibility of duplicate messages
being echoed by different applications. The maximum
length for <words> is 80 bytes.
Comments: In a multi-user environment, the printer may respond to
many different status requests. Since the status messages
are buffered in the printer until they are received, the
current application may receive status messages that were
requested by a previous application. (This happens in
situations where the application requests information, or
unsolicited status is enabled, and the application closes
before receiving the status messages.)
Parameter Functional Range Default
<words> Roman-8 characters 33 – 255,
<SP>, <HT>
N/A
7-14 Status Readback Commands
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