Multiple NMEA 0183 devices connected?

[Patrick Randall]

My Garmin GPS/Plotter has 2 NMEA capable ports - port one is occupied by a Garmin sounder module, port two is connected to a Raytheon Autohelm NMEA in.I also want to connect a Yeoman (paper) chart plotter to the port 2 NMEA in/out of the GPS.Can I just "stack up" the two NMEA connections on the same terminals so for example, both the Autopilot NMEA in and Yeoman plotter NMEA in are connected to the port two set of GPS NMEA out terminals?

 

[Rod Sparks]

I think that you are stuck unless you hook up a switch go between the the two devices that you want to hook up to your second NEMA port.If you want the output go to into Nobeltec or another navigation program on your laptop. You can run multiple NEMA connections provided you use your USB ports.I use a cheap USB Hub and some Serial-to-USB adapters. I plug the USB Hub into the USB port on on my laptop. I do not have contention issues. I connect my GPS, depth, water temp and boat speed into Nobeltec realtime. Works great.

 

[O salt]

NEMA Connections

NEMA out put you can stack, with limited length. NEMA input only one.

 

[Gregg]

Which Garmin

GPS/plotter are you using?How about connecting NMEA port 2 to a terminal strip? You would then have several terminals to tap off of, maybe add a DSC VHF also?

 

[Derek Rowell]

O_salt, on a NMEA system...

... you can only have one "talker" (device sending data), but you can have several "listeners" (devices receiving data from the talker). Therefore you can connect several DATA IN lines together, as long as they are connected to a single DATA OUT (on one of the instruments). This is the opposite of what O_salt states.On my boat the GPS is the talker, and the autopilot, computer, and instruments are listeners.You can buy NMEA multiplexors that will allow multiple talker configurations.Derek

 

[O salt]

I think we are saying the same thing.

Derek, I think we are saying the same thing. I am referancing the device. On the NEMA imput you can only connect one device. If you are outputting a NEMA signal you can connect multipule devices to this output as long as you limit the length of the cable.For exsample, on the NEMA out of my GPS, I can connect my autopilot and Laptop. But I can not connect my Laptop to the Autopilot because it's NEMA input is already connected to the GPS.