Specifications

5.11 Electronics unit

Apart from some distributed sensor electronics all electronics is concentrated in the electronics

unit. The unit is located below the hatchcover. It features a modular design that allows adding

and/or upgrading of existing and future sensor and communication options electronics. A C-

programmable microprocessor forms the heart of the electronics unit and in fact the whole buoy.

In this section the purpose of the connectors on the outside and the location of the printed

circuit boards on the inside will be explained. For testing and diagnosing the buoy direct

communication with the microprocessor is possible. In table 5.11.1 the various request

commands and associated message outputs are detailed.

5.11.1 Connectors on the outside

Figure 5.11.1 shows the connector block (in the middle) of the electronics unit. The

functionality of each connector is discussed in parallel below.

Before the electronics unit will do anything it requires power. In normal operation power

is supplied by the buoy batteries through the 14-pin main hatchcover connector, for the WR-SG

and the DWR-G or 19-pin connector for the DWR-MkIII. The DWR-G 0.4 m is the only

exception with a 7-pin connector or 12-pin connector in case rechargeable batteries are used.

Slide it on and turn the screw-ring to fasten.

For servicing, the unit may also be powered externally through the black (−) and red (+)

jack or, in case of a DRW-G 0.4 m, a 2.5 mm female plug (centre −). Any DC power supply

with an output voltage in the range 12-30 V and capable of delivering over 2.5 W will do (25 W

with satellite communication option, Argos/Orbcomm). The external supply will also take over

from the internal battery source if its voltage exceeds that of the batteries. Maximum battery

voltage is about 12 V (DWR-G 0.4 m), 21 V (WR-SG both diameters and DWR-G 0.9m), 24 V

(DWR-MkIII both diameters) and 25V (DWR-G 0.7 m).

Communication with the buoy processor is possible through a RS-232 9-pin female

connector. Refer to the Console subsection 5.11.4 for the communication format, input

commands and output messages.

All signals from the MkIII motion and temperature sensors are fed to the electronics unit

through the main hatchcover connector. Sensor readings of other buoy models (water

temperature and WR-SG motion) are passed to the electronics unit via I

C. The I

C protocol can

easily accommodate future sensors.