NCR 74 OFX (7874), Руководство пользователя

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5-46 Chapter 5: Programming
Interface Control
The Interface Control parameter permits control of the transfer of data between the
scanner and the host terminal. The options are None, enable ACK/NAK, enable
XOn/XOff, and enable both ACK/NAK and XOn/XOff.
If enable ACK/NAK is selected, each message sent to the host terminal must be
acknowledged before sending the next message. Receiving the message properly
causes an ACK to be sent, and if there are any errors, a NAK is sent instead and the
scanner sends the message again. Also, any valid message other than NAK or
XOn/XOff, if enabled, serves as an ACK as long as the message from the scanner is
completed before the host terminal starts sending the valid message to the scanner.
An XOff message turns the scanner transmitter off until the scanner receives an XOn
message. An XOn message can be received at any time. If the scanner is sending a
message when it receives an XOff, since these messages can be received any time, data
transmission stops after sending the current byte. When the scanner receives the next
XOn, 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 5 tag.
Check Digit
The Check Digit parameter permits control of the transmission of UPC–A, UPC–E,
EAN–8, and EAN–13 check digits. Scan the appropriate Hex tag ( Hex 0 to Hex F ) to
independently enable or disable UPC–A, UPC–E, EAN–8, and EAN–13 check digits.
The default is Hex 1 —Enable UPC–A, EAN–8, and EAN–13; Disable UPC–E.
RS232 Prefix Byte
22774
Prefix Byte A
ASCII Code
B
0
Disable
1
Enable
0 - 7
Hex Character
(ASCII Code Chart)
0 - F
Hex Character
(ASCII Code Chart)
0
Default
2
Your Program
Prefix Byte
A
RS-232
Prefix Byte
2 2
ASCII Code
B