Overview
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.
Connector:
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.
Cables:
Cable assemblies up to 30 meters long can use oil filled cable:
Longer lengths will require smaller, more flexible cable types: See FALMAT Technical Data Sheet.
Important notes:
- It is critical for PIs to work with MARS O&M staff to ensure that their cable assemblies are suitable for successful deployments.
- Cable assembly must use the pinout described on this page.
Electrical
The pin assignments for the science port:
Pin No. |
Description |
1 |
Not used |
2 |
Not used |
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.
- Continuous power:
- 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.
- Continuous power:
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.
- A typical receive circuit is shown below:
- The 1 PPS is driven by this 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.
Illustration of instruments connecting to the main science node with or without a Science Instrument Interface Module (SIIM):
