Lowrance Connectors

Electrical and electronic topics for small boats
thill
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Joined: Sun Sep 03, 2017 10:59 pm

Lowrance Connectors

Postby thill » Sat Mar 09, 2019 10:16 am

I had an older Lowrance [multi-function] unit that failed. It had gray plugs on the rear panel. I found a great deal on a like-new used Lowrance LMS 337C with blue plugs in the back.

The existing 200/50 transducer plugs right in, and works properly. Great!
The [external] GPS [device] does not plug in. The [external GPS device] has a four-pole plug, whereas the [LMS337C] has a five-pole terminal that says "NETWORK."

Q1: is there a network cable that plugs into the [LMS337C] on one end and to [external GPS device] on the other end?

Q2: is there any way to adapt [the two devices]?

Q3: or, are they completely incompatible?

This is my first networking system, and I know ZERO about them, so please forgive my ignorance.

Q4: [Where] can I do some reading so I can get at least a minimal understanding of how these systems work?

Thanks.

jimh
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Re: Lowrance Connectors

Postby jimh » Mon Mar 11, 2019 3:02 pm

thill wrote:I found a great deal on a like-new used Lowrance LMS 337C...


The LMS337C is very obsolete. It went of production about 14 years ago. I can imagine that a used one would be quite a bargain.

jimh
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Re: Lowrance Connectors

Postby jimh » Mon Mar 11, 2019 3:03 pm

thill wrote:...the [LMS337C] has a five-pole terminal that says "NETWORK."


You are probably describing a NMEA-2000 port on the multi-function display device.

jimh
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Re: Lowrance Connectors

Postby jimh » Mon Mar 11, 2019 3:06 pm

thill wrote:...This is my first networking system, and I know ZERO about them...any suggestions on where I can do some reading, so I can get at least a minimal understanding of how these systems work...


Re Q4: you can read my short and concise primer on NMEA-2000. It is available at

NMEA-2000 Networks and Modern Outboard Engines
http://continuouswave.com/whaler/reference/NMEA2000.html

It explains the basics of constructing a NMEA-2000 network and will give you links to more information.

jimh
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Re: Lowrance Connectors

Postby jimh » Mon Mar 11, 2019 3:09 pm

thill wrote:...Is there a network cable that plugs into the [LMS337C] on one end and to [my old external GPS device] on the other end?


Re Q1: without knowing what sort of external GPS device you had previously, it is impossible to answer your question. Your old external GPS device might have been a non-NMEA-2000 receiver. It might have just output serial data in NMEA-0183 protocol.

You do not mention what sort of multi-function device you had previously. It is impossible to know what sort of device that other unit would have used as an external GNSS receiver or antenna.

Generally modern multi-function devices include an internal GNSS receiver, so they do not need to be connected to an external GNSS receiver.

I recommend you get the owner's guide for the LMS337C device you have. It should give you guidance about whether or not it has an internal GNSS receiver.

When Lowrance first used NMEA-2000 they employed non-standard connectors. They called these connectors the LowranceNET BLUE connectors. That is probably what the LMS337C has. Those are obsolete. Later Lowrance changed to a standard connector, which is called the DeviceNET Micro C connector, but Lowrance renamed these as LowranceNET RED connectors. Later Lowrance changed those connectors to BLACK, but did not give them a new name. They were just called "NMEA" connectors. The DeviceNET Micro C connector remains the standard connector for NMEA-2000. The obsolete LMS337C may not have any DeviceNET MIcro C connectors. It may have the obsolete LowranceNET BLUE connectors.

You may be looking for an obsolete LowranceNET BLUE NMEA-2000 connector to an UNKNOWN GPS DEVICE connector. There is a real possibility that no such cable existed, and that your old external GPS device is not a NMEA-2000 device. Also, if you did find a cable, it may be expensive, perhaps more than the cost of a used GNSS receiver with NMEA-2000 and the proper connector.