4. Exception Reporting, Sense Data,
and Recovery
About Exception Reporting, Sense Data, and
Recovery
This chapter supplies information about Acknowledge Reply, which the IPDS uses for exception
reporting.
The chapter begins with general information followed by tables of the exception reporting codes for the
printer. The tables contain details about the specific exceptions. The chapter concludes with a section on
printer counter adjustments.
• When you have questions about codes from the printer, use this chapter instead of the exception-
reporting chapter in the Intelligent Printer Data Stream Reference. Although the two chapters are
similar, this chapter contains only those exception codes that the printer returns.
General Reply Rules
IPDS uses the Acknowledge Reply command to return both positive and negative replies to the host.
Positive messages are Acknowledge Replies. The negative messages (exception messages) are NACKs
and are sent as sense-byte information in the special data area. For more information about
Acknowledge Replies, see "Device Control Command Set", IPDS Technical Reference 2.
The following general rules apply to printer replies:
• The printer reports a data-stream exception with a NACK. Only one exception can be returned in
each NACK.
• The printer sends an ACK or a NACK in response to an Acknowledgement Required (ARQ) flag. If
there is an exception, the printer sends a NACK without receiving an ARQ.
• If the printer receives a command requesting an acknowledgement, it expects the host to wait for
the acknowledgement before sending more commands.
• Any data received after an exception is reported is discarded until all queued NACKs have been
either sent to the host or cleared by an appropriate linklevel command. An exception on a
command can be reported before receiving the entire command data. When an Alternate
Exception Action (AEA) or Page Continuation Action (PCA) is not to be taken, the next data
received should be part of a new command. Otherwise, an 8001..00 exception may result. The
printer might not discard the remaining bytes in a command with an error when reported.
Therefore, the next data received should be the start of a new command. As a result, begin the host
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