How to interface



There are eight primary science ports on the MARS node.  In general, a Principal Investigator (PI) will be assigned one science port.  Each port provides 48 VDC, 375 VDC, a 10/100Base-T TCP/IP Ethernet connection, and a pulse per second (PPS) precision timing signal.  The port interface is detailed below.


The science port connector is a 12-pin, wet mateable, 45 degree, flying ROV style connector from Ocean Design, Inc. (ODI). ODI does not provide a part number for the connector. ODI will work with MARS PIs to develop a complete cable assembly.


Front view


Side view

Longer lengths will require smaller, more flexible cable types. The choice of cables and connectors that the ROV must handle are critical to the success of your deployment. We will be happy to work with you to properly specify these elements.

Molded cable

Molded cable


Oil-filled cable

Important: It is critical for PIs to work with MARS Operations and Maintenance staff to ensure that their cable assemblies are suitable for successful deployments.

Cable assembly must use the pinout described on this page.


The pin assignments for the science port:

Pin No. Description
1 Reserved
2 Reserved
3 RX+
4 RX-
5 1 PPS+
6 1 PPS-
7 TX+
8 TX-
9 375 VDC+
10 375 VDC-
11 48 VDC+
12 48 VDC-

Electrical specifications:

  • 48 VDC:
    • Continuous power:
      100 W maximum.
    • Peak power:
      Additional power can be provided to meet short term needs.  Please discuss your power requirements with MARS O&M staff.
    • Inrush current:
      10A absolute maximum; 3 millisecond max. duration.
  • 375 VDC:
    • Continuous power:
      500 W maximum.
    • Peak power:
      Significantly more power can be provided at 375 VDC to meet short term needs.  Please discuss your power requirements with MARS O&M staff.
    • Inrush current:
      15A absolute maximum, 3 millisecond max duration.

Note: Please monitor your equipment’s inrush current.  We have observed many commercial power supplies that draw as much as 50A on power up, regardless of steady state current requirements.

  • 1 PPS
    • The 1 PPS is driven by this circuit:


Click image for specification

Specification for 4N37 optocoupler.

  • A typical receive circuit is shown below:

Suggested user interface circuit

Ethernet Communication

The communication channel for all MARS science ports is a standard 10/100Base-T Ethernet port using TCP/IP protocol.  Each MARS science port is assigned a Class C subnet which can provide up to 245 individual IP addresses to a single science port (11 are reserved for internal MARS functions).  MARS O&M staff will work with PIs to assign appropriate IP addresses.

At Sea

Research Vessel Western Flyer
2016 departure/arrival times
Research Vessel Rachel Carson
Research Vessel Paragon
Emergencies and contacts
Onboard cruise log
Policies and operating guidelines
Cruise planning
Marine operations policies
Departure/arrival times
Early departure
Elevator payload limits
Hazardous materials
Homer beacon policies
Lab use and chemical safety
NILSPIN ™ oceanographic ropes
Push core policies and description
RHIB operations
Rigging policy
Science party size
Cruise planning
R/V Western Flyer cruise planning
Checklist of Supplies
Cruises outside home port
Data and video: formats and specifics
Departure/arrival times
early departure
Hazardous materials
Precruises and postcruises
RHIB operations
ROV dive time definitions
ROV users checklist
Safety Management System
Science party guidelines
Scuba diving
Ship to shore communications
R/V Rachel Carson cruise planning
R/V Paragon cruise planning
Marine operations policies
Remotely operated vehicles
ROV Ventana
ROV Doc Ricketts
Mini remotely operated vehicle (ROV)
Autonomous underwater vehicles
Gulper autonomous underwater vehicle
Seafloor mapping AUV
Long-range autonomous underwater vehicle Tethys
Investigations of imaging for midwater autonomous platforms
Benthic Rover
Autonomous surface vehicles
Wave Glider
Wave Glider-based communications hotspot
2015 Expeditions
2014 Expeditions
2013 Expeditions
2012 Expeditions
Cabled observatory
About MARS
MARS contacts
MARS science experiments
How to connect to MARS
MARS contacts
How to interface
MARS site description
MARS instrument deployment
MARS biology
MARS technology
MARS connector wiring
MARS node description
More ocean observatory resources
Local notice to mariners
Mooring data
Research tools
Administration & planning
Cruise planning
Marine operations technicians
Marine operations policies