Interface specifications for instruments wishing to connect to the OASIS
controller.

1. Power.

OASIS is capable of providing up to 2.5 amps of nominal "12 volt" power,
either switched on and off as required, or left on continuously.  Note that
instruments should be capable of normal operation over a 11-15 volt range.
OASIS is NOT capable of providing other voltages, such as 24v.

2. Serial interface.

OASIS can provide a "three wire" serial interface.  True RS-232 voltage
levels ONLY.  Common baud rates up to 38,400 baud are supported.
0-5 volt "TTL", or 0-12 volt "Fake RS-232", connections are NOT supported.

3. Analog interface.

OASIS has a very limited number of external analog channels available.  These
are single ended, 0-5 volt 12 bit channels.  If the use of one of these
analog channels is desired, check with OSG.

4. Physical interface.

The connector to mate with OASIS is currently the SeaCon AWQ-4/24MP.  The
pin out is:

4: +12v
3: RXD
2: TXD
1: GND

RXD and TXD are in respect to the OASIS controller, i.e. TXD is data coming
out of OASIS to an external instrument.

5. Isolation.

All instruments shall NOT have any portion of their internal electrical system
connected to the case, or "seawater ground".

6. Logistics.

Although it is not a requirement, it is highly desirable to avoid the following:

A) Instruments that require a BREAK to wakeup or for other purposes.  Useage
of BREAK is problematic for a variety of reasons.

B) Instruments that cannot be configured to give data upon demand, but
require OASIS to listen for the data at pre-defined intervals.  Although this
has been done in the past, the situation is less than optimum, and the OASIS
to instrument connection is often lost requiring manual intervention.

C) Instruments that require an external wakeup signal.  OASIS can provide
both "sourcers" and "sinkers" for wakeups, but they require an extra pin in
the interface connector that may or may not be available.