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Author Topic:   MARETRON NMEA-2000 DeviceNET
jimh posted 04-15-2014 12:32 PM ET (US)   Profile for jimh   Send Email to jimh  
Perhaps the nicest NMEA-2000 network cabling and accessories are made sold by Maretron. (The cable and connectors are probably sourced by Maretron from an OEM cable and connector manufacturer; I'd be surprised if Maretron actually has a factory making these cables and connectors.) Their Micro DeviceNET connectors employ metal locking collars, and the insulation used on the cables is often more supple and flexible than other brands. The insulation is also blue or gray, which may give a more pleasing appearance than the usual black cables.

Maretron feature a power cable that splits the network power into two segments, allowing for higher power consumption for the total network or for power isolation in the network. They also have four-port drop cable junction boxes to eliminate use of multiple network-T connectors in the backbone.

One caution when considering Maretron wiring and accessories: they make two distinct series of connectors, one called Micro and one called Mini. The Micro series is typically the one most used on small boats, and will be compatible with most other vendors. The Mini-series will probably not be useful on a small boat.

To add a little more confusion, Maretron makes a hybrid called MICRO/MID. This cabling uses larger conductors for the power distribution (16-AWG instead of 22-AWG), which can be useful in some situations to reduce voltage drop or to comply with regulations (regarding minimum size of wire for power distribution, I presume). The connectors are still the Micro connectors and these devices will interoperate with Micro devices.

The best way to get into Maretron NMEA-2000 wiring is by a starter kit. Maretron has a NMEA-2000 starter kit (M2KKIT) which retails for about $120. The M2KKIT includes:

--one Micro/Mid Powertap Tee CF-SPWR05-CF

--two Micro Tee CM-CF-CF

--two Micro Terminators TR-CM

--one 3-meter Cordset CM-CG1-CF-03.0


This will create a minimum network backbone with power, termination, and two open ports for connecting devices. To expand from this configuration you can add additional Network-T connectors (Micro Tee CM-CF-CF, about $21 ) or a four port junction box (CM-CF-4, about $80) and short cable (CM-CG1-CF-01.0, about $24) id=749749 id=1243250 id=749956

It is important to note that if you want to maintain the lower-voltage drop, higher current rating of the MICRO/MID cabling, you have to use the appropriate pre-made MICRO/MID cables, which use 16-AWG conductors for power. See Mid%20Bulk%20Fields%20Cords%20Datasheet.pdf

These cable are not always stocked and sold by big-box marine retailers. Most retailers only have in stock the MICRO cord sets, which use 22-AWG conductors for power. See Micro%20Cords%20Tee%20Pwr%20Datasheets.pdf

jimh posted 04-18-2014 07:57 AM ET (US)     Profile for jimh  Send Email to jimh     
I spent some time looking for DeviceNET wiring cables and accessories as provided by non-marine manufacturers, to see if there was much difference in price. There was some difference in price, but not what I expected. A few things sold as DeviceNET for industrial use were very slightly less expensive, such as a terminator plug, but, overall, the price of the industrial cables was actually higher in most cases than the marine cables. I believe that is due to the industrial cables often being made with more exotic insulation, such as Teflon or Halogen-Free material, while the marine cables were just plain PVC insulation. It seems like some of these cables must be used in industrial food preparation or some other plant environment which was particular about the insulation, and the cables were generally more expensive than marine NMEA-2000 cables. The industrial cables and connectors did not seem to offer much opportunity to save money on a typical NMEA-2000 installation on a small boat, and tended to be much harder to source from vendors. Since there was very little or perhaps no cost difference, to buy these products through the industrial electronic sales channel would not be a good choice, either for cost or for simplicity of getting the right cable.
jimh posted 04-18-2014 08:02 AM ET (US)     Profile for jimh  Send Email to jimh     
In the process of searching for DeviceNET cables and connectors, I really did not find much use of the term "Micro-C" for the connectors. Usually the connectors were referred to as just "DeviceNET MIcro" connectors. Perhaps the "C" is just a shorthand for circular. The connectors are also often called M12 connectors, a reference to the specification of the metric thread of the locking collars, I believe. The DeviceNET connectors are also used with more than just a five-pole contact arrangement.
jimh posted 04-18-2014 09:15 AM ET (US)     Profile for jimh  Send Email to jimh     
The cabling used in DeviceNET is generally referred to by four terms:

DeviceNET THICK = Red-Black power 15-AWG; Blue-White data 18-AWG (and that 15-AWG is not my typing error)

DeviceNET MID = Red-Black power 18-AWG; Blue-White data 20-AWG

Device NET THIN = Red-Black power 22-AWG; Blue-White data 24-AWG

Device NET FLAT = Red-Black power 16-AWG; Blue-White data 16-AWG

That standard is a little different than the NMEA-2000 standard for cable, which seems to be

NMEA-2000 HEAVY = Red-Black power 16-AWG; Blue-White data 18-AWG

NMEA-2000 LIGHT = Red-Black power 22-AWG; Blue-White data 24-AWG

The Maretron cables seem to have their own specifications. They use the connector term "micro" to describe one cable, and the cable term "mid" to describe the other, but both the Maretron cables differ in their wire sizes from the NMEA standard cables.

Maretron MICRO = Red-Black power 22-AWG; Blue-White data 22-AWG

Maretron MID = Red-Black power 16-AWG; Blue-White data 20-AWG

Cf.: pdf Mid%20Bulk%20Fields%20Cords%20Datasheet.pdf

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