Sending NMEA to 2 PC Apps

[WayneS]

I want to have my GPS NMEA data fed to 2 PC applications simultaneously. Chartplotter and Passage Planner (So that I can keep continuous watch on progress against plan)

I am thinking that to do this I will have to split the GPS feed into 2 serial ports on the PC.

Has anyone else done this?

Cheers

Wayne


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[MarkV]

Why can't both apps read the same port, so long as neither are trying to write to it?

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[rogerthebodger]

If the apps are running on the same computer each app must read from seperate port to avoid lost data in each app so yes 2 ports. all you need is a cable with one in and 2 out with parallel connections.

Roger

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[Beagle]

Have you tried it by using only one port?

Since Windows is not a 100% true multi tasking platform, it doesn't make sence to me. In theory, it should be possible using just 1 port.

But than again, have to try it myself this weekend........

<hr width=100% size=1>Climate is what you expect, weather is what you get

 

[extravert]

> Since Windows is not a 100% true multi tasking platform

It is, and has been for a while.

> In theory, it should be possible using just 1 port.

Each application will be trying to open a serial port for exclusive access. The second will fail with 'Port already open' if the same one is used for both.

As said above, the NMEA input can be fed into 2 serial ports, as long as both applications don't try to write to the port simultaneously.

Parts available cheaply from Maplin. Bit of soldering required.

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.

 

[steve28]

input would need to be optoisolated to stop the serial info begin corrupted. Use the nmea splitter as posted by alexl in previos post and the dual serial ports as mentioned in the above posts.
The Dual serial ports are needed as only one port can be used by one program.


The above has been tested by me proir to this post but using a single gps to two seperate chart programs running on the same computer, one reading gps info from com1 and one from com2.Again using the nmea splitter as well.



steve

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[extravert]

If one talker (GPS) is connected to 2 listeners (the serial ports on a PC) there is no need for opto-isolators or a NMEA splitter. The serial data cannot get corrupted if the 2 PC applications are listening only and not talking. The TxD connections on the PC side don't need to be connected to anything if the PC applications are not producing data.

If data are going back from both the PC applications to the GPS, then a NMEA multiplexer is needed. The original poster does not make this clear.

An opto-isolator won't stop corruption. It's there purely to protect against over-voltage or spikes. The opto-isolator goes pop instead of the device it's connected to.

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.

 

[Benbow]

>> input would need to be optoisolated to stop the serial info begin corrupted. <<


Run that by me one more time ????


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[Aeolus_IV]

Optical isolators make no interpretation of the signals, they simply convert the input signal into light, then the light back into an electrical output signal. If the input signal is rubbish, so will the ouptut be (GIGO as we used to call it). As extravert said, it only there so that an electrical fault at one end isn't propergated through the wire to the other.

For this situation clever electronics are not needed, simple connect the ground and Tx from the talking device to the Rx and Ground of both ports of the PC (I guess that there may need to be one or two other wires at the PC end), then the two applications can each have their own port with their own copy of the data.

Jeff.



<hr width=100% size=1><A target="_blank" HREF=http://users.swing.be/FDB/centurion/index2.html>Centurion 32 Web site</A>

 

[snowleopard]

i'd have a look in the manuals to see if either of the programs can be set to relay the signals to another port. it doesn't have to be a physical port so e.g. one could read from com1 and write to com3 then the other could be set to read from com3.

failing that a friendly programmer might be persuaded to write a little application to read from com1 and write to com3 & com4.

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[rrees]

Use Serial Splitter by http://www.eltima.com/
I have used it works a treat and no hardware to mess about with

RR

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