NCR 74 OFX (7874) - Check Digit; Interface Control; RS232 Prefix Byte

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
