NCR RealScan 7802, Руководство пользователя

Страница: 34 / 94

NCR RealScan 7802 Price Verifier User Guide
06/03 497-0425530 Release E 34 of 94
Protocol Implementation Rules
1.
Mode values changed during a query session are only retained during that session.
2.
The host can make “permanent” changes to mode values for query sessions by
connecting to the ProductInfo protocol port (Port 1283) of the client and setting the
values. As long as that connection is maintained, the new values are used in all
further queries.
3.
Whether a “permanent” change can survive a power cycle of the client is
implementation-dependent. Clients may provide special functions to record mode
information in non-volatile storage.
4.
Query sessions are best kept limited to information that is displayed immediately,
so further queries can be answered.
5.
Mode values that start or end with white space must be sent enclosed in double
quotes. These quotes are removed when the value is stored. Double quotes within
the string are treated as part of the value.
6.
When using double-byte font files such as the Kanji font (7640 characters), text
string must be defined as Big-Endian or Little-Endian depending on the server.
NCR RealScan 7802 Implementation Rules
1.
The RealScan 7802 maintains an asynchronous ProductInfo server. The host can
open a connection and send messages to this listener at any time.
2.
The RealScan 7802 sends carriage return/linefeed pairs to indicate an end–of–line
(<NUL> marks end–of–string) to accommodate various host computers, but accepts
either or both.
3.
When started up, the RealScan 7802 makes a copy of the setup information stored in
the non-volatile memory. Changing a mode’s value modifies this copy and is the
source of mode values when a mode request is executed. Setting a mode does not
preserve the new value in non-volatile memory; the new value(s) must be
specifically committed. A second copy of the setup information is kept as the
current value set. This copy is modified by the realscan.ini file contents.
4.
The values that are read for modes are those default values and may not reflect the
current operational values. This occurs when the initialization file overrides the
default values. Setting values sets what is recorded to non-–volatile memory, but
may not affect immediate operations.
5.
Changing a mode’s value may not cause the RealScan 7802 to immediately change
its behavior; some changes require the unit be reset before they take effect.
6.
Several modes are immediately affected when changed: Timeout, TrivialComm,
SendUnitID, SendError, SendResponse, TextBackgnd, TextForegnd, and
QueryPrefix.
7.
The text display modes (TextHPos, TextVPos, TextRows, TextCols) can be forced to
take effect by setting the TextReset mode to TRUE.
8.
The QueryPrefix can contain binary information. To set a QueryPrefix with binary
values, use a ‘C’ language format string for the value. The RealScan 7802 accepts
“\x” followed by two hex digits as a single character with the value of the two hex
digits; no other sequences are recognized.
9.
When powered up, the RealScan 7802 attempts to register with the host system. If it
cannot do so, it waits 10 seconds and tries again. After each failure, it waits one
second longer than the previous time, ad infinitum. Additionally, whenever the
RealScan 7802 detects that the initialization file has changed, it makes one attempt
to re-register. This permits a host computer that has gone down to force all the
RealScan 7802’s to register without knowing which or how many the
RealScan 7802‘s are on the network. Registration can be selectively disabled.