Can you name all of the signals in the original 25-pin RS-232 connector?
What is the actual circuit? Draw a diagram of the circuit and indicate the required value of each voltage source.
Pins 9, 10, 11, 18 and 25 are unassigned/reserved. The rest are:
Pin Abbreviation Source Description
1 PG — Protective Ground
2 TD DTE Transmitted Data
3 RD DCE Received Data
4 RTS DTE Request to Send
5 CTS DCE Clear to Send
6 DSR DCE Protective Ground
7 SG — Signal Ground
8 CD DCE Carrier Detect
12 SCD DCE Secondary Carrier Detect
13 SCTS DCE Secondary Clear to Send
14 STD DTE Secondary Transmitted Data
15 TC DCE Transmitter Clock
16 SRD DCE Secondary Received Data
17 RC DCE Receiver Clock
19 SRTS DTE Secondary Request to Send
20 DTR DTE Data Terminal Ready
21 SQ DCE Signal Quality
22 RI DCE Ring Indicator
23 — DTE Data Rate Selector
24 ETC DTE External Transmitter Clock
