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    Netport(R) II Print Server: Parallel and Serial Port / Cable Issues

    Contents:

    • PARALLEL CABLE LENGTH
    • PARALLEL PORT PIN ASSIGNMENTS
    • NOTES ON THE SERIAL PORT
    • SERIAL CABLE WITH HP PRINTER
    • SERIAL CABLE WITH APPLE LASERWRITER
    • GENERIC SERIAL CABLE
    
    

    PARALLEL CABLE LENGTH

    
       The maximum supported length of the parallel printer cable is 6 feet. 
    
       Using the NetPort(R) II print server with a cable that exceeds 6 feet
    
       may result in printing problems such as; garbage charaters, not printing
    
       at all or intermittent printing.
    
    
    
    

    PARALLEL PORT PIN ASSIGNMENTS

    
       The NetPort(R) II follows the Centronics parallel port standards.  The
    
       rule of thumb is that if the printer will work attached to a PC, then it
    
       should work with the NetPort II print server.
    
    
    
       i=input to printer
    
       o=output from printer
    
    
    
       Pin #Signal
    
       1    i    strobe-        (low for handshake)
    
       2    i    Data bit 0
    
       3    i    Data bit 1
    
       4    i    Data bit 2
    
       5    i    Data bit 3
    
       6    i    Data bit 4
    
       7    i    Data bit 5
    
       8    i    Data bit 6
    
       9    i    Data bit 7
    
    
    
        10  o    ack-           (normally high - low when ready for next
    
                                character)
    
    
    
        11  o    busy           (normally low, high to hold off handshaking)
    
    
    
        12  o    papererror     (normally low, high for paper problems)
    
    
    
        13  o    select         (normally high, low for off line)
    
    
    
        14  i    autofeed-      (held high)
    
    
    
        15  o    error-         (normally high, low for error)
    
    
    
        16  i    init-          (held high)
    
    
    
        17  i    selectin       (held high)
    
    
    
        18-3     Various
    
    
    
       At least one ground signal from the printer must be connected to at
    
       least one of the NetPort's pins 18-25 via the parallel cable.  The
    
       printer grounds occur somewhere in the range of 18-36.  Some
    
       manufacturers put strange functions on these pins.  Any pin in the 18-36
    
       range that is not ground should not be connected to the NetPort.
    
    
    
       If busy or papererror is high, or select or error is low, NetPort will
    
       not print.  The timing of the handshake signals strobe-, ack-, and busy
    
       can cause problems.
    
    
    
    

    NOTES ON THE SERIAL PORT

    
       1.   The cable must be a serial printer cable (a modem cable will NOT
    
            work with printers).  Some printer manufactures require specific
    
            cable pinouts.  Check your printer manual for the recommended
    
            cable.  This document has three cable pinouts that may be helpful.
    
    
    
       Note: Serial printer cables and modem cables are NOT the same and can
    
       NOT be used interchangeably for printing purposes.  A modem cable
    
       connects a DTE (data terminal equipment) device to a DCE (date
    
       communication equipment) device.  This requires a cable that connects
    
       TXD to TXD, RXD to RXD etc.  Whereas, a serial printer cable connects
    
       TXD to RXD, RXD to TXD, CTS to RTS etc.  Refer to the NetPort(R) II
    
       print server manual for detailed pin out examples of serial printer
    
       cables.
    
    
    
            The maximum cable length is 50 feet.  Using the NetPort II with a
    
            cable that exceeds 50 feet may result in printing problems such as:
    
            garbage characters, not printing at all or intermittent printing.
    
    
    
       2.   The handshaking parameters must be set the same for the NetPort II
    
            and the printer.  By default the NetPort's parameters are set to
    
            9600 baud, NONE parity, 8 databits, 1 stopbit, XON-XOFF handshake. 
    
            If the printer is not set to all of the above parameters, either
    
            the NetPort II print server or the printer must be changed.  To
    
            change the printer consult your user's manual.  To change the
    
            NetPort II, use Netport Manager to reconfigure the port settings. 
    
            Select Configure/Hardware/Ports and set the serial port options to
    
            the required settings.
    
    
    
       Note: The default parameter will work with the HP Laserjet printer.  Rev
    
       003 of the Ethernet manual is incorrect. Also, we have found that the
    
       cable is the frequent cause of serial printing problems.
    
    
    
       Note: When using the NetPort II serial port in Print Server mode with HP
    
       Plotter, it is usually preferred to use the XR handshake.
    
    
    
    

    SERIAL CABLE WITH HP PRINTER

    
       The following serial cable has been tested and will work with the HP
    
       Laserjet series printers and plotters:
    
    
    
       DB-9(NetPort)            DB-25(HP laserJet)
    
       DCD 1--------------------4  RTS
    
       RXD 2--------------------2  TXD
    
       TXD 3--------------------3  RXD
    
       DTR 4--------------------5  CTS & 6 DSR
    
       GRN 5--------------------7  GND
    
       DSR 6 & CTS 8------------20 DTR
    
       RTS 7--------------------8
    
    
    
    

    SERIAL CABLE WITH APPLE LASERWRITER

    
       The following serial cable has been tested and will work with the Apple
    
       laserWriter series printers:
    
    
    
       DB-9(NetPort)            DB-25(Apple LaserWriter)
    
       RXD 2--------------------2  TXD
    
       TXD 3--------------------3  RXD
    
       GND 5--------------------1  GND & 7 GND
    
       DSR 6 & CTS 8------------20 DTR
    
       RTS 7--------------------5 CTS & 6 DSR
    
    
    
    

    GENERIC SERIAL CABLE

    
       The following serial cable is a generic RS232 serial cable and will work
    
       with many standard printers:
    
    
    
       DB-9(NetPort)            DB-25(serial printer)
    
       RXD 2--------------------2 TXD
    
       TXD 3--------------------3 RXD
    
       GND 5--------------------7 GND
    
       DSR 6 & CTS 8------------20 DTR
    
       RTS 7 -------------------5 CTS & 6 DSR
    
    

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