Timewave DSP-232, Operating Manual, Page: 16 / 271

Chapter 2 Power Supply and Computer Installation
Don’t use a “null modem” cable. This type of cable flips pins 2 & 3 so that pin 2 on one end of the cable is
connected to pin 3 on the other end (and vice versa.) Use a cable that has “straight through” connections like the
ones used to connect computers to a telephone modem since as far as your computer’s concerned, the DSP
is a
modem.
Once you’ve tested the cable to make sure it’s pinned correctly, plug one end into your computer’s serial port and
the other end to the RS-232 I/O port on the back of the DSP, then proceed to the
System Start-up and Loopback Test
later in this chapter.
Note : The enclosed computer cable was designed to connect directly to a 9-pin, IBM-PC/XT/AT
compatible computer’s RS-232 port. Some less-common machines are listed below.
Apple Computers
If you own an Apple Macintosh or Powerbook-type computer, simply purchase a standard mini-DIN8 to DB-9
modem cable.
Dumb Terminals
If you have an RS-232 “dumb” computer terminal, you may need to change the gender of the cable provided with
your DSP. This can be done with an inexpensive double-male RS-232 gender changing adapter available from
Radio Shack (part number 26-1388, Radio Shack Port Adapter) as well as other computer dealers.
The Computer
If the type of computer you plan to use with the DSP wasn’t mentioned earlier in this chapter, you may find
specific connection information below. You’ll also need a communications program to use with your computer. See
The Control Program section below for information regarding communication programs for many of the above
machines.
Many computers require a serial port adapter card that incorporates the necessary RS-232-C interface circuitry; The
IBM-PC is a good example of this. Computers that don’t have a serial port or permit use of a suitable adapter or
level converter can’t be used with the DSP.
Other Computers with RS-232 Ports
If your computer has an RS-232 port, consult your computer manuals to see which pins are used for TxD, RxD and
signal ground. Read the manufacturer’s recommendations for connecting the serial port to a telephone-type modem
and connect your DSP the same way.
The DSP-232 is configured as Data Communications Equipment (DCE)—it transmits data on pin-2. Most
computers and terminals are configured as Data Terminal Equipment (DTE) transmitting data on pin-3.
If your computer is configured as Data Terminal Equipment (DTE), use the supplied RS-232 cable with a gender
changing adapter, if necessary. These are available from Radio Shack (part number 26-1388) and other computer
stores.
September, 05 2-3