VT100.net: Digital VT102 User Guide

Table 6-5 Full-Duplex with Data Leads Only (FDX A) Signals
Pin | Name (Mnemonic) | CCITT / EIA | Switch | Description
--- | --- | --- | --- | ---
1 | Protective ground (PGND) | 101/AA | - | Connects to terminal chassis. Also connects to external ground through third wire of power cord.
2 | Transmit data (TXD) | 103/BA | S6 | From VT102: When switch S6 is on (closed), TXD transmits serial characters and breaks generated by terminal. TXD is in mark state when no characters are transmitted.
NOTE: When S6 is on (closed), switch S7 must be off (open).
3 | Received data (RXD) | 104/BB | - | To VT102: RXD receives serial characters from the computer.
4 | Request to send (RTS) | 105/CA | S1 | From VT102: When switch S1 is on (closed), RTS is on if terminal is on-line and off if terminal is off-line.
5 | Clear to send (CTS) | 106/CB | S2 | To VT102: When switch S2 is on (closed), CTS is only used to turn CTS indicator on or off. The on condition of CTS turns CTS indicator on; the off condition turns CTS indicator off.
NOTE: When S2 is on (closed), switch S3 must be off (open).
6 | Data set ready (DSR) | 107/CC | - | To VT102: DSR turns DSR indicator on or off. The on condition of DSR signal turns DSR indicator on; the off condition turns DSR indicator off.
7 | Signal ground (SGND) | 102/AB | - | SGND is common ground reference potential for all connector signals except protective ground. SGND connects to protective ground conductor.
20 | Data terminal ready (DTR) | 108.2/CD | - | From VT102: DTR is on when the terminal is on-line and off when the terminal is off-line or performing a line disconnect. When on, the modem can usually answer calls (modem auto answer option). When off, the modem usually disconnects and does not answer calls.
23 | Speed select (SPSD) | 111/CH | S10 | From VT102: SPSD is on when the receive speed SET-UP feature selection is greater than 600 baud. SPSD is off when the speed is 600 baud or less.