STATUS POLLING 7
This chapter explains how to use status polling.
There are two types of Status Polling:
¨
Inquiry Request—information about the readiness of the printer.
¨
Job Request—information about the current (or last received) job
downloaded to the printer.
Inquiry Request (ENQ)
An ENQ character acts as a request for printer status information. You can
send an ENQ in front of, in the middle of, or immediately following any packet
downloaded to the printer. An ENQ is a command that can be executed as part
of a packet or sent on its own (using a communications program). An ENQ is
processed immediately. The ENQ character is user defined.
The ENQ character does not appear as a visible character; however, we are
representing the ENQ character as E .
Inquiry Response
Printer status is returned to the host in a 3-byte (3-character) sequence. The
first byte is the non-printable user-defined ENQ character, which is not visible
on the response. The second and third bytes are printer status codes. See the
ENQ Reference Tables for the meaning of bytes 2 and 3.
Example: E AB
The status codes (A and B in this case) are ASCII equivalents to the
hexadecimal bits that represent the various types of status responses. This
response indicates that the printer is online (Character A) and that there is a
stock fault (Character B).
Example: E ??
Indicates that this is the first ENQ response since the printer was turned on.
Send another ENQ immediately to receive the printer’s status.
Example: E @@
Indicates the printer is offline.
STATUS POLLING 7-1
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