Index Everest-D, Service Manual

Page: 48 / 51

Version 2.0
Page 48 Index Braille Printer Company
INDEX EVEREST SERVICE MANUAL
6.1.1 RS232-C circuit summary.
Pin InterchangeCCITT Description Type Direction
1 AA 101 Protective ground gnd n/a
7 AB 102 Signal or common gnd gnd n/a
2 BA 103 Transmitted data data To DCE
3 BB 104 Received data data From DCE
4 CA 105 Request to send ctrl To DCE
5 CB 106 Clear to send ctrl From DCE
6 CC 107 Data set ready ctrl From DCE
20 CD 108.2 Data terminal ready ctrl To DCE
22 CE 125 Ring indicator ctrl From DCE
8 CF 109 Rec’d line sig. detect ctrl From DCE
21 CG 110 Signal quality detect ctrl From DCE
23 CH 111 Data sig. rate sel DTE ctrl To DCE
23 CI 112 Data sig. rate sel DCE ctrl From DCE
24 DA 113 Trans sig elem timing DTE time To DCE
15 DB 114 Trans sig elem timing DCE time From DCE
17 DD 115 Rec’r sig elem timing DCE time From DCE
14 SBA 118 Secondary trans. data data To DCE
16 SBB 119 Secondary rec. data data From DCE
19 SCA 120 Secondary request to send ctrl To DCE
13 SCB 121 Secondary clear to send ctrl From DCE
12 SCF 122 Secondary RLSD ctrl From DCE
6 Cables
6.1 Serial communication
The EIA Standard, RS232-C, is the interface between Data Terminal Equipment(DTE), and Data
Communication Equipment(DCE). DTE is typically a computer, printer, or terminal. DCE is
generally a modem. RS232-C
is the latest version of the standard and outlines the set of rules for exchanging data between
computers and peripherals.
The standard has four categories of leads: ground, data, control, and timing. Protective ground is
used for protection from electrical shock, with Signal ground used as a reference for the other
categories of leads. The data leads are used for transmitting and receiving data. Control leads
control the interface, direction of data flow, and indicate
the status of the attached equipment. The timing leads are used only in synchronous environ-
ments. Usually when printers are being attached to computers, these leads are not used.