Installation
Seanet SCU v5
0581-SOM-00002, Issue: 05
13
© Tritech International Ltd.
3.2. Communication Configuration
Fitted inside the SCU, located at the front panel, is the SCUv5 Main Board. This is a multi-
purpose board that houses the bulk of the circuitry from the superseded AIF PCB. This
includes the ARCNET interface, for communications with the subsea sensor heads, and the
RAT interface. The Main Board is also populated with the Memory Card Reader, Port Status
LEDs and hardware for COM Ports A to D. The SCUv5 Main Board will appear in the Setup
table as Node 252 which replaces the Node 255 for the superseded AIF Card.
Full details of all the connections are contained in Appendix B,
. Normal communications with the subsea devices is via a customised version of the
ARCNET network system and requires a good quality balanced twisted pair cable.
An optional RS232 interface can be provided to allow telemetry connection through a fibre
optic system capable of 115kbit·s
-1
transmission. The RS232 interface is available in the
guise of an RS232 to ARCNET converter PCB that is installed in a dry pod inside the
ROV. Alternatively, an intelligent 4000m pressure rated Junction Box will provide the RS232
interface to the network of SeaKing ARCNET devices.
Note
The SeaKing range of Subsea Sensors are designed to work from a smoothed
DC power supply of 20-72V DC (Absolute Maximum 72V DC) when fitted with a
COMV6 PCB. For more details, please contact
Tritech International Ltd
.
Caution
SeaKing units fitted with a COMV5 MOD A PCB, or earlier, have an operating
voltage range of either 18-28 VDC or 18-36 VDC. Please contact
Tritech
International Ltd
for more information and advice.
If using a rectified transformer PSU, the output of the PSU must have a filter capacitor of not
less than 470μF, for each head being powered. If an unregulated PSU is used, then make
sure that the voltage value measured at the head is in the range 20-72v DC, both in power off
and running conditions. If powering the head(s) down a long lead or umbilical, the maximum
recommended loop resistance of the power line must not exceed 10Ω for one head, 5Ω for
two heads, and 3Ω for three heads. If the supplied voltage is less than 20V DC the head
may not operate correctly.
Caution
Never try to make
Tritech International Ltd
sonar heads work down a long cable
by increasing the PSU output voltage above the recommended voltage.
For detail of the appropriate termination requirements for a
Tritech International Ltd
ARCNET
network please refer to Appendix C,
Use with Ethernet Sonars
The motherboard Ethernet port is capable of driving a single Ethernet device, such as a
Gemini imaging sonar or profiler, or it can be coupled to a network switch to enable multiple
sonars to be operated. A specially designed Gemini Hub unit is available from
Tritech
International Ltd
which enables multiple Gemini profilers and other sensors to be attached
through the Ethernet port.
Extra software may be required to operate the Ethernet sonars, please contact
Tritech
International Ltd
for more details.