NCR 7890, User Manual

Page: 151 / 217

Programming Your 7890 Scanner
RS-232 Parameters - 2
5-76 User’s Guide
An XOff message does not permit the transmission of
data until the scanner receives an XOn message. An
XOff message can be received any time. If the scanner is
sending a message when it receives an XOff, data
transmission stops after sending the current byte. When
the scanner receives an XOn message it sends the
remainder of the message. The scanner does not
acknowledge XOff and XOn messages with ACK or
NAK messages.
Select the interface by scanning the appropriate Hex 0
through Hex 3 tag. The default is None.
The Check Digit parameter permits you to control the
transmission of UPC-A, UPC-E, EAN-8, and EAN-13
check digits. Scan the appropriate Hex 0 through Hex
3
tags to enable or disable UPC-A, UPC-E, EAN-8, and
EAN-13 check digits. The default is enable UPC-A,
EAN-8, and EAN-13 and disable UPC-E. This option
also effects OCIA Long on later versions of the firmware
(497-0301339 and higher).
The Variable Length Indicator (VLI) and Bit 6 End Of
Message (EOM) parameter permit you to identify the
length, or end, of each message sent to the host terminal
or PC. The VLI gives the length of a message and Bit 6
EOM identifies the end of a message.
The VLI includes itself and all bytes through the BCC. It
immediately follows the Prefix Byte. Not using the
Prefix Byte causes the VLI to be the first byte in the data
message.
Check Digit
VLI and Bit 6 EOM