| Pinbelegung X4, X5 (TTY, 20mA) Pinout X4, X5 (TTY, 20mA) |
| Signalname / Bezeichnung Signal Name / Description | Kurz Short | IN / OUT IN / OUT | 15-polig 15-pin |
| Externe Masse External mass | Mext MEXT | | 1 1 |
| Empfangsdaten minus (LED-Kathode) Receive data minus (LED cathode) | TTY IN - TTY IN -- | IN IN | 2 2 |
| Stromversorgung +5VDC Power +5 VDC | +5V +5 V | | 3 3 |
| Stromversorgung +24VDC Power +24 VDC | +24 +24 | | 4 4 |
| Interne Masse Internal mass | Masse Bulk | | 5 5 |
| Sendedaten plus (Transistor Kollektor) Transmit data plus (collector transistor) | TTY OUT+ TTY OUT + | OUT OUT | 6 6 |
| Sendedaten minus (Transistor Ermitter) Transmit data minus (transistor investigation) | TTY OUT- TTY OUT | OUT OUT | 7 7 |
| Externe Masse External mass | Mext MEXT | | 8 8 |
| Empfangsdaten Plus (LED Anode) Plus receive data (LED anode) | TTY IN+ TTY IN + | IN IN | 9 9 |
| Masse für +24VDC Mass for +24 VDC | | | 10 10 |
| 20mA Stromquelle Sender 20mA current source transmitter | | | 11 11 |
| Interne Masse Internal mass | Masse Bulk | | 12 12 |
| 20mA Stromquelle Empfänger 20mA current source receiver | | | 13 13 |
| Stromversorgung +5VDC Power +5 VDC | +5V +5 V | | 14 14 |
| Interne Masse Internal mass | Masse Bulk | | 15 15 |