From the NSEPRO:     
     
     Serial Port.  If you will be using a serial port for a communications
     channel, you need to be very careful of the cable that you use. The most
     common serial cabling problems are:

     *    Misconfigured cables (incorrect cable pinouts)

     *    Mismatched handshaking on either side of the cable

     *    Cabling too long (signal is degrading)

     Check that no other boards are using the same hardware interrupts as your
     serial port (usually IRQ 4 for COM1 and IRQ3 for COM2). If you will be
     communicating faster than 19.2Kbps, or if you will be using RPRINTER
     under Windows, you may need to purchase a special high-speed serial port
     (such as one from Hayes) to communicate reliably.

     Serial Cabling Pinouts.  There are two types of serial port handshaking
     that can be used with NetWare: software handshaking and hardware
     handshaking. Software handshaking uses control codes (XON and XOFF) in
     the data to control the flow of the data through the cable. Hardware
     handshaking uses an extra pair of serial port wires (DSR and DTR) to
     handle the flow control of data in the cable.

     Two types of cabling connectors are usually used with serial cables. The
     first type has a DB25 (25 pin) connector on the PC side. The second type
     has a DB9 (9 pin) connector on the PC side. Figure 5 gives the ideal
     serial cabling pinout configurations.

     Figure 5: Serial cabling pinouts.

            +---------------+--------------++---------------+--------------+
            !Computer (DB25)!Printer (DB25)!!Computer (DB9) !Printer (DB25)!
            +---------------+--------------++---------------+--------------+
Using       !       2       !      3       !!       2       !      2       !
            +---------------+--------------++---------------+--------------+
software    !       3       !      2       !!       3       !      3       !
            +---------------+--------------++---------------+--------------+
handshaking !       7       !      7       !!       5       !      7       !
            +---------------+--------------++---------------+--------------+
(XON/XOFF)  !               !   4-5-6-8    !!               !   4-5-6-8    !
            +---------------+--------------++---------------+--------------+


            +---------------+--------------++---------------+--------------+
            !Computer (DB25)!Printer (DB25)!!Computer (DB9) !Printer (DB25)!
            +---------------+--------------++---------------+--------------+
Using       !       2       !      3       !!       2       !      2       !
            +---------------+--------------++---------------+--------------+   
hardware    !       3       !      2       !!       3       !      3       !
            +---------------+--------------++---------------+--------------+
handshaking !      5-6      !      20      !!      6-8      !      20      !
            +---------------+--------------++---------------+--------------+
(DSR/DTR)   !       7       !      7       !!       5       !      7       !
            +---------------+--------------++---------------+--------------+
            !               !   4-5-6-8    !!               !   4-5-6-8    !
            +---------------+--------------++---------------+--------------+


     It is rare to have the cable you need when you need it. Here are a few
     suggestions for when you need to use a store-bought cable whose pinouts
     may not exactly match those above, or when you need to make your own
     cable:

     1.   You must have at least one ground pin. Choose pin 7 over pin 1,
          since pin 1 is grounded via the system's power cable, and the
          printer and PC may get their power's ground from a different source.

     2.   You must have both CTS and RTS. These are pins 2 and 3 in most
          cables. The cable needs to be set up as a null modem cable,
          requiring the CTS and RTS pins to be reversed at either end of the
          cable.

     3.   You should only need a ground pin (1 or 7) and CTS/RTS (2 and 3) in
          a null modem configuration to give you a XON/XOFF (software
          handshaking) cable.

     4.   A DSR/DTR (hardware handshaking) cable is essentially the same as a
          XON/XOFF cable, but also has to have the DSR and DTR pins (usually
          pins 6 and 20 on a DB25). These signals must be crossed in a null
          modem configuration.

     5.   Novell's PSERVER and RPRINTER query the line status of pin 5, and
          DOS often queries pin 6. To pull these cabling pins electrical
          signals high, we highly recommend you tie together pins 4-5-6-8 at
          the printer end (not at the PC end). If you don't, you may find the
          printer mysteriously going off-line on the PSERVER console.

     6.   If a store-bought cable has additional cabling pins, find out what
          they are connected to using an ohm-meter or similar device. If none
          of the additional pins are using the pins mentioned above (ground,
          CTS, RTS, DSR, and DTR), there is a good chance it may work. Often,
          testing is the only sure way to know.