RS-232 Devices¶
The RS-232 interface supports legacy serial devices that use RS-232 voltage levels (typically ±3–15 V). This is common on older marine equipment with DB-9 or DB-25 serial ports.
Wiring¶
Connect the device to the RS-232 3-pin terminal block:
| Pin | Signal | Description |
|---|---|---|
| 1 | GND | Signal ground |
| 2 | RX | Device transmit → HALSER receive |
| 3 | TX | HALSER transmit → device receive |
Signal Direction
TX and RX are labeled from HALSER's perspective. Connect HALSER's TX to the device's RX, and vice versa.
Signal Levels¶
RS-232 uses inverted logic with wider voltage swings than TTL:
- Logic high: −3 V to −15 V
- Logic low: +3 V to +15 V
- No hardware flow control (RTS/CTS) — only TX, RX, and GND are available
Compatible Devices¶
RS-232 is suitable for:
- Older chart plotters with serial ports
- Legacy marine instruments with DB-9 connectors
- Industrial serial devices