RS 232-interface

Connecting peripheral equipment to computers is all very well provided the signal levels are compatible. This is not always the case and often some form of interface, to convert the signals from one level to another, has to be added. Certain require- ments have to be met as the output signals of most peripheral equipment conform to the RS 232/V 24 standard. The interface shown in the circuit diagram is intended for use with the Junior Computer (PA7 and PBO refer to the series input and output of the JC), but it can also be used with any other computer. The signals are converted to TTL from the RS232 level by transistor T1 and from TTL to RS232 by N1 and IC2. The latter are converted to a level of 24 Vp-p. PA7 6 k ... 8 k internal pull up •SV OV FULL/HALF DUPLEX N: SI T1 BC 547B RS 232 connector 1 2 34 7 12 V RS 232-interface PBO 02V -12V 12V 80601 Ni" IC1.1 7401