Error Handling - Printronix S828 Programmer's Manual

Programmer Manual PTX‐S828
END (End): The END command terminates the image block state. The printer remains in the page state.
WT (Write Text): This command is repeated at this point in the sequence to illustrate that additional text
data can be added to the page. In addition to zero or more of the WT commands, graphics data, bar code
data, or additional image data could also be included on the page.
IO (Include Overlay): The IO command causes a previously stored overlay to merge onto the current
page. This overlay now prints on the current page.
IPS (Include Page Segment): The IPS command causes a previously stored page segment to merge
onto the current page. An ID in this command specifies the selected page segment. The selected page
segment now prints on the current page.
EP (End Page): The EP command causes the printer to leave the page state and return to the home
state. Printronix that this command contain an acknowledgment request to verify successful execution of the
page data.
ACK (Acknowledgment Reply): If the previous command had the ARQ bit on, the printer responds with
the ACK reply to inform the host of successful execution of all the previous commands. This reply
indicates to the host that the printer has accepted all the page data, and all selected segments, images, or
overlays have successfully printed.
Chapter 5, "IPDS Programming Information," contains a more detailed description of all the IPDS commands.

Error Handling

An exception (error) occurs when the printer detects an invalid or unsupported command, control, or
parameter value in the data stream received from the host. The IPDS error handling structure assigns a
unique exception code to each type of error. The printer sends these codes to the host, as sense bytes, in
the NACK (negative acknowledgment reply). See Chapter 6, "IPDS Exception Reporting Codes," for a
description of the exception codes.
The host can control how the printer responds to the exceptions. The Exception Handling Control
(see"Exception Handling Control (EHC)") order permits independent control over three exception
handling functions:
● The exceptions to report with a NACK reply
● The implementation of Alternate Exception Actions (AEA) when a valid parameter value is received but
not supported by the printer
● The termination or continuation procedure to follow if the alternate error action is not taken or if there is
no alternate error action associated with this error.
The host application program can use the Exception Handling Control order to accomplish many specific
control capabilities necessary in data printing environments. For example, through the proper selection of
settings, it is possible to:
● Enforce control over printing of page information
● Enable automatic skipping of data types not supported by the printer
● Suppress the return of meaningless or redundant exception reports when alternate actions are
acceptable to the user.
The host can issue the Exception Handling Control order in any printer state. This allows the host to
manage exception processing at any level desired by the host application.
Chapter 4 IPDS Commands 113 260071‐001A