Compuprint 4247-Z03 Programmer Manual - Manual (Page 148)

The first asynchronous NACK is the only one reported, even though other synchronous NACKs may be
detected before the first NACK is reported. If the printer has a pending exception (the exception has
occurred but has not yet been reported), the printer reports the exception when exception handling control
directs.
Alternate Exception Action: Byte 3 of the EHC subcommand controls Alternate Exception Actions.
v Bits 0-6: Reserved
v Bit 7: Alternate Exception Action (AEA) control
This bit defines how printer processing continues when a data stream error occurs.
If the bit is set to 0, the printer continues processing with the Alternate Exception Action. If the error has
no Alternate Exception Action defined, the printer continues as though this bit contained a 1.
If this bit is set to 1 or no AEA is defined, the printer reports the error regardless of the value in the
Exception Reporting byte above. The printer continues processing as defined by the contents of the
Exception Presentation Processing byte below.
Exception Presentation Processing: Byte 4 of the EHC subcommand defines what the printer does
when exceptions occur in any state except home state.
v Bits 0-5: Reserved
v Bit 6: Page Continuation
If bit 6 is 0, the printer does the following:
– Terminates processing of the page, overlay, or page segment data
– Prints as much of the previously processed data as possible
– Enters home state.
If bit 6 is set to 1, the printer ignores bit 7 (Error Page Print) after taking a skip and continue action. The
printer remains in the current state and treats subsequent commands as No Operation (NOP) until it
encounters either the next valid command or a terminating condition.
1. Skip and Continue Action
Skip and Continue Actions are attempts by the printer to skip the remainder of the IPDS block
containing the exception and to print subsequent blocks or text on the page (if any).
The printer treats all subsequent commands other than Any State commands (NOP, SHS, STM, and
XOA) as No Operation (NOP) commands until it encounters either the next valid command or a
terminating condition. The printer remains in page, page segment, or overlay state. If the printer is in
a block state, the End command is the next valid command that returns the printer to page, page
segment, or overlay state. When the next valid command is encountered, the printer begins normal
processing again. The exception that caused the skip and continue action is reported when the end
of the page is reached, when an XOA command sets home state, or when a command with an ARQ
is received. The following conditions determine the next valid command:
– If the exception occurs in a Write Text command, a Load Font Equivalence command, or an
Include Page Segment command, the next valid command is End Page, Set Home State, or
XOA Discard Buffered Data.
– If the exception occurs in a block state, the next valid command is End.
– If the exception occurs in an Any-state command, the next valid command is the command that
follows.
– If the exception occurs in any other command, the next valid command is one of the following (if
supported):
- Write Text
- Include Overlay
- Include Page Segment
- Write Text Control
- Write Image Control
- Write Image Control 2
- Write Bar Code Control
128 Programmer Manual