Twinleaf Differential Serial (TDS)
The Twinleaf differential serial interface conforms to the RS422 standard with additional specifications for power supply and synchronization.
Physical interface
An 8p8c (RJ-45) connector is provided for connections using standard CATx ethernet-style cable.
| Pin | Signal | Wire color |
|---|---|---|
| 1 | TX+ | Orange/White |
| 2 | TX- | Orange |
| 3 | RX+ | Green/White |
| 4 | +15-48V | Blue |
| 5 | Ground | Blue/White |
| 6 | RX- | Green |
| 7 | PPS+ | Brown/White |
| 8 | PPS- | Brown |
Digital signal nominally employ ±3.3V differential signaling. Twinleaf uses LT2685 transceivers to drive all three TX, RX, and PPS signal lines, providing high ±25V common mode tolerance and ±15 kV ESD protection.
Power may be supplied up to an absolute maximum of 60 V to overcome resistance in long cables.
The PPS signals are not required for operation, but are used to discipline and synchronize an oscillator at the sensor.
Applications
The TDS interface supports long cable lengths, up to 1 km with appropriate considerations for system power and cable resistance. Pictured above is a 100 m spool of neutrally buoyant cable attached to a VMR sensor. The cable passes through a slip ring and connects to a SYNC8-TDS host unit.