GTCO AccuTab II - Users Guide - Manual (Page 29)

AccuTab II 29
Cabling
Cabling carries the data from one device to the other. A majority of RS-232C cables have
either male 9-pin or 25-pin subminiature D connectors on their ends to match female
connectors on the equipment. The AccuTab II is supplied with an 8-pin-mini-din-to-9-pin-D
serial cable and a 9-pin-to-25-pin adapter.
Data Terminal Equipment (DTE), such as printers, digitizers and computers, usually (but not
always) transmit data on Pin 2 and receive data on Pin 3. Data Communications Equipment
(DCE), such as modems, generally transmit data on Pin 3 and receive data on Pin 2. Thus,
connecting a terminal (DTE) to a modem (DCE) may be as simple as connecting them with a
straight-through cable that is wired pin-to-pin (i.e., 1 to 1, 2 to 2, etc.). This figure shows
such a cable. The AccuTab II Controller is typically connected in this manner using the
cable supplied by GTCO CalComp by Turning Technologies.
Connecting DTE to DTE, or DCE to DCE, may require a different strategy to get the data on
the correct wires. The below figure shows a cable that can work in this situation. It is called
a null modem cable and it fools both devices into thinking they are talking with the right
kind of receiver. This cable routes Pin 2 to Pin3 and Pin 3 to Pin 2.