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Chapter 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.
n
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.
7-1