Echo Command - Brother HL-Series Technical Reference Manual

Revision C 16/01/96

7.4. ECHO Command

The ECHO command requests the printer to send back a specified message, in order to ensure that the
printer is ready for communication with the application and that the received answer from the printer is
what the application requested. The application must send this command before starting PJL
communication.
After sending the ECHO command, the application must ignore any status information from the printer
before it receives the response for this command, because not receiving the response for this command
means that the printer is still processing the previous job and its status information is for the previous
job environment. When the application receives the correct response for the requested ECHO
command, the printer is now ready for the application and you can be sure that the status information
following is for the requested command by the application.
Syntax :
@PJL ECHO [< words >] [<CR>]<LF>
Response Syntax :
@PJL ECHO [< words >] <CR><LF>
<FF>
•
< words >
The beginning of this parameter must be a printable character. Then this parameter consists of
characters from ASCII 33 to 255 and space characters, and horizontal tab characters.
This < words > parameter can be written without quotation marks as this is not a string of variables.
The parameter is recommended to be unique, distinguishable words from other print jobs, such as
the time determined by the real time clock and user name, so as to confirm the received message
from the printer is definitely the answer for the ECHO command which the application sent.
The length of the < word > must be within 80 characters.
Parameters :
Example :
The application sends the following example to the printer :
<ESC>%-12345X@PJL <CR><LF>
@PJL COMMENT the ECHO command follows <CR><LF>
@PJL ECHO This is a sample 22:03:00 <CR><LF>
<ESC>%-12345X
The printer sends back the answer for the above ECHO command :
@PJL ECHO This is a sample 22:03:00 <CR><LF>
<FF>
After receiving the above answer, all the messages from the printer are the requested information from
the application, except for unsolicited status information.
Parameter
< words >
ASCII 33 to 255, <SP>,
<HT>
Chapter 3 "PJL" - 38
Valid characters