Browse Prior Art Database

Auto Selective Printer Interface

IP.com Disclosure Number: IPCOM000111369D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Kurishita, Y: AUTHOR [+2]

Abstract

Disclosed is a circuit for printer interface which supports three kinds of interface mode: parallel interface, serial RS232 interface, and serial RS422 interface. By sensing a signal line , some parallel interface signals are assigned automatically for the other serial interface. Therefore, three major interfaces can be used with only one connector by this method.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 75% of the total text.

Auto Selective Printer Interface

      Disclosed is a circuit for printer interface which supports
three kinds of interface mode: parallel interface, serial RS232
interface, and serial RS422 interface.  By sensing a signal line ,
some parallel interface signals are assigned automatically for the
other serial interface.  Therefore, three major interfaces can be
used with only one connector by this method.

      The concept of this circuit is shown in the Figure.

      An analog switch (e.g., FET) changes the three signals of the
parallel interface (PE: paper end, ERROR: error, SEL: select) to
RS232 signals (TXD:Tansmit data, RTS:Request to Send, DTR:Data
Terminal Ready) by sensing the volt age level of RXD (Receive Data)
signal line (1).  This signal line is low level (under -2V) normally
at RS232 mode, and not connected at parallel interface.  So the level
sensing logic can detect the difference and the output signal is used
for the mode control signal (2).  Also a certain delay is needed for
interface mode change because the RXD signal level is changed
according to coming data during Data Frame span (7).

      The Receive Data signal of the serial controller is switched
for serial interface (RS232 and RS422) by this control signal (3).
Therefore, the related connector pin of RS422 cable must be open like
the parallel interface.

      The input signals of the parallel interface (e.g., AF:Auto
Feed, SelIn:Select In) use the same signal lines at R...