PacComm TINY-2 - Page 148

APPENDICES RS-232 Signal tabie
RS-232 Signal Table
F
The EIA RS-232C Standard
The Electronic Industries Association (EIA) RS-232C standard defines
the interfacing between data terminal equipment and data communica-
tion equipment employing serial binary data interchange. Electrical
signal and mechanical aspects of the interface are well specified. The
complete RS-232C interface consists of 25 data lines. This would
seem to be enough signals for a complex parallel communication line,
but many of the 25 lines are very specialized and few are undefined.
Most computer terminals only require from 3 to 5 of these lines to be
operational.
Because RS- 232C was originally intended for data communications
equipment, a few lines must be swapped between a computer and
terminal if no modem of other data communications equipment is used.
These wires are swapped within the cable connecting the two devices.
This line is called a null modem cabie.
Pin Description
1 Protective Ground
2 Transmitted Data
3 Received Data
4 Request to Send
5 Clear to Send
6 Data Set Ready
7 Signal Ground (Common Return)
8 Received Line Signa! Detector
9 (Reserved for Data Set Testing)
10 (Reserved for Data Set Testing)
_ 11 Unassigned (See section 3.2.3)
12 Sec. Rec'd. Line Sig. Detector
13 Sec. Clear to Send
14 Secondary Transmitted Data
15 Transmission Signal Element Timing (DCE Source)
16 Secondary Received Data
17 Receiver Signal Element Timing (DCE Source)
18 Unassigned
19 Secondary Request to Send
20 Data Terminal Ready
21 Signal Quality Detector
22 Ring Indicator
23 Data Signal Rate Selector (DTE/DCE Source)
24 Transmit Signal Element Timing (DTE Source)
25 Unassigned
TINY-2/MICRO-2 Technical Ref., 2 Ed © 1989, PacComm, Inc.