Author Topic: How to split COM port  (Read 3854 times)

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Offline Arjen

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How to split COM port
« on: September 10, 2011, 06:36:14 AM »
My Weatherstation is a WMR968 and I use Weather Display at a older Windows 2000 computer. I have renewed my WMR968 and got the program Virtual Weather Station base edition. I'm interested to compare both programs for a long time simultaneous. For that reason both programs must be connected to the same COM port. I'm looking for a freeware splitter for com ports. By Google I found professional programs, but expensive for my trial. So where can I find a simple com port splitter or is there another solution? For example redirect to a virtual ports?

Arjen
Uitgeest,
The Netherlands

Offline WeatherHost

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Re: How to split COM port
« Reply #1 on: September 10, 2011, 06:52:39 AM »
If you have a PCI slot available, consider something like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16815317002


Offline 92merc

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Re: How to split COM port
« Reply #2 on: September 10, 2011, 09:42:04 AM »
On the VWS side, we have Virtual VP.  I don't think that works for WD, but on the site there are links to some TCP to Serial bridges.  I'd bet some combination of those might work.
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Offline xykotik

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Re: How to split COM port
« Reply #3 on: September 10, 2011, 11:13:02 AM »
...both programs must be connected to the same COM port...

You mean the same PHYSICAL connector, correct?  Is the problem that two applications can't call the same logical COM?  While it's not an OS, I read of people running two programs (ie Cumulus and WeatherLink) simultaneously, and the (Davis) console has to be in serial mode for that to work, so it doesn't seem like a console/com-port issue, it just talks to the PC.  Could WD and VWS do the same thing with your WMR968? 

Just throwing that out as an idea.


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Offline vellecadp

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Re: How to split COM port
« Reply #4 on: September 10, 2011, 11:53:28 AM »
I am running two programs and feeding them data from a single weather station - I am using a program called "XPort" which allows virtual COM Port creation.  Works very well.  Good Luck!

Dennis

Offline Bushman

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Re: How to split COM port
« Reply #5 on: September 10, 2011, 12:16:10 PM »

Offline Axelvold

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Re: How to split COM port
« Reply #6 on: September 10, 2011, 12:38:21 PM »
On the VWS side, we have Virtual VP.  I don't think that works for WD, but on the site there are links to some TCP to Serial bridges.  I'd bet some combination of those might work.

Virutal VP does work with WD, I use it with VWS, WD, Weatherlink and VPLive
Lars Magnusson
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55 57' 41" N / 13 6' 1" E
WX Station: Davis Vantage Pro2 Plus

Offline chief-david

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Re: How to split COM port
« Reply #7 on: September 10, 2011, 12:57:07 PM »
ditto on Virtual VP. I am running 4 programs
Free 30 day trial too.
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Robbinsdale, MN 55422@ 45 degrees North Latitude.
http://weather.rms.rdale.org/

Offline neondesert

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Re: How to split COM port
« Reply #8 on: September 10, 2011, 05:09:52 PM »
As an user of VirtualVP myself, I would highly recommend it. 

That said, the OP's weather station is a OS WMR968
Someone correct me if I'm wrong but I don't think that VirtualVP can
be used with this station.  :?:
Larry
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Offline SlowModem

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Re: How to split COM port
« Reply #9 on: September 10, 2011, 05:26:08 PM »
As an user of VirtualVP myself, I would highly recommend it. 

That said, the OP's weather station is a OS WMR968
Someone correct me if I'm wrong but I don't think that VirtualVP can
be used with this station.  :?:

From the website:

Quote
VirtualVP is a software application that lets you connect up to 4 weather programs to a single Davis Vantage Pro 1 or 2 weather station (console or Envoy).
Greg Whitehead
Ten Mile, TN

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Offline Arjen

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Re: How to split COM port
« Reply #10 on: September 10, 2011, 05:48:09 PM »
Thanks a lot for your overwhelming response!
That program Virtual VP I was looking for. Not expensive and fits my purpose. Thanks again,

Arjen
Uitgeest,
The Netherlands

Offline neondesert

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Re: How to split COM port
« Reply #11 on: September 10, 2011, 05:54:47 PM »
Thanks a lot for your overwhelming response!
That program Virtual VP I was looking for. Not expensive and fits my purpose. Thanks again,

Arjen

I don't think Virtual VP will work with your station, Arien.

As Slow Modem has pointed out:

From the website:
Quote
VirtualVP is a software application that lets you connect up to 4 weather programs to a single Davis Vantage Pro 1 or 2 weather station (console or Envoy).
Larry
"But it's a DRY Heat!"


Offline moehoward4

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Re: How to split COM port
« Reply #12 on: September 10, 2011, 06:44:34 PM »
VirtualVP only works with the Vantage Pro, maybe the Vue?            Jack
WMII CS   2 VP2's   WL, VWS, Cumulus, VVP   4" Stratus   and no website.....

Offline C5250

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Re: How to split COM port
« Reply #13 on: September 11, 2011, 09:52:39 PM »
"Splitting" a com is not as easy as it might seem. In general serial ports are intended for direct communication between two devices and there is rarely provision for a third device to be involved. In some cases you may get away with it, if the third device (or software) only listens to the serial data stream. VirtualVP gets around this by acting as a buffer, VirtualVP is the only software in such a setup that actually communicates with the Davis weather station, and then it uses virtual serial ports to send data to other programs. It will not work with an OS station though, as it has no knowledge of the OS serial protocol.

Some weather software programs have a "listen only" option, if one of the programs you are using has such an option, it may be possible to make it work.

As it was brought up, the Vue uses the same protocol as a VP/2, so VirtualVP will work with any of them. The only thing I'm not certain about is whether Steve has added support for "LOOP2" yet.

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Offline Weather Display

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Re: How to split COM port
« Reply #14 on: September 11, 2011, 10:23:23 PM »
you can use a physical 'Y" splitter
as the WMR968 sends data without any request needed
but
only if the DTR and RTS lines are held high
so those control lines would need to be in that state through the com port splitter

Offline C5250

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Re: How to split COM port
« Reply #15 on: September 11, 2011, 11:31:41 PM »
So, for an OS station, it could be as simple as using a few 422/485 adapters?
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Offline Arjen

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Re: How to split COM port
« Reply #16 on: September 12, 2011, 09:58:16 AM »
First I had read the description of VirtualVP and I got the opinion that is what I was looking for. After I replied with a positive answer, later on I spent time to install. But I did not succeed to make a serial splitter with VirtualVP possible. And I'm wondering about that. The WMR986 is only to read. There is no handshaking with the weatherstation and the programs. And also the signals are NMEA, that is a universal protocol. Does the VirtualVP need a special token provided by the VantagePro? In that case another weatherstation may not possible. Is my conclusion all right? In that case I don't put effort in trials/investigation.

Thanks in advantage,

Arjen
Uitgeest,
The Netherlands

Offline SLOweather

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Re: How to split COM port
« Reply #17 on: September 12, 2011, 11:47:59 AM »
I successfully split the feed from a WMII to 2 serial ports on the same computer with a B&B Electronics Serial Data Tap.



Now I use it to split a GPS stream in my truck. That's the same basic idea as splitting the stream from your weather station. There are DIP switches to control handshaking lines and such.

Keep in mind that to use this, you will need 2 physical serial ports on the computer.

Offline Weather Display

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Re: How to split COM port
« Reply #18 on: September 12, 2011, 03:51:45 PM »
IN response to Argen
the WMR968 data is not NMEA
and Virtual VP will not work with the WMR968 station, due to it not expecting the data protocol differences from a VP

Offline C5250

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Re: How to split COM port
« Reply #19 on: September 12, 2011, 11:56:25 PM »
Does the VirtualVP need a special token provided by the VantagePro? In that case another weatherstation may not possible. Is my conclusion all right? In that case I don't put effort in trials/investigation.

As was stated above, VirtualVP will only work with Davis weather stations.

Not sure where your NMEA comment came from, that is a serial communication protocol used by GPS's and is not relevant in this case.
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Offline mackbig

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Re: How to split COM port
« Reply #20 on: September 13, 2011, 07:54:00 AM »
Kind of the opposite of what I am doing with my Brultech.   Two devices that output to serial, by using the "MUX-2 multiplex adaptor for RS-232 connection" it sends to a single com port.  The Y splitter should work fine with an OS, assuming dual serial port on PC (or single with an extra usb-serial cable, or I guess two usb-serial cables)

Andrew - Davis VP2+ 6163, serial weatherlink, wireless anemometer, running Weather Display.  Boltek PCI Stormtracker, Astrogenic Nexstorm, Strikestar - UNI, CWOP CW8618, GrLevel3, (Station 2 OS WMR968, VWS 13.01p09), Windows 7-64

Offline vellecadp

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Re: How to split COM port
« Reply #21 on: September 14, 2011, 01:50:50 PM »
I have not tried XPORT with my old WMR968, however it works beautifully with my Davis unit.

Basically, you set up the programs to use different COM Ports - in my case Weather Display is set to use COM9 and Cumulus is set to use COM7.  The XPORT basically takes my real COM4 and then splits it to both COM7 and COM9 (Virtual Ports)

The data is not recognized as NEMA format so there is some note at the bottom of the screen in XPORT that states it is unrecognized data.

So to use, set up your programs with the Virtual COM Port numbers, start them both, then start XPORT - it should autoconfigure and viola!

Good luck!

Dennis

Offline Weather Display

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Re: How to split COM port
« Reply #22 on: September 14, 2011, 03:21:42 PM »
you would be better though to use VVP than a Y splitter with a Davis station
to avoid problems with the 2 programs requesting different things at different times (and expecting certain responses) from the station
especialy for history data
VVP takes care of all that for you