Instruction manual

7
STATUS POLLING
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
.
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:
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:
??
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:
@@
Indicates the printer is offline.
The following graphics can be used as a quick reference for the Status of Byte #2 and Byte #3.
Byte #1 is the non-printable user-defined ENQ character.
Status Polling 7-1