Topic: Davis VP 2 Serial Logger Cable to PC Issue

[MichiganWX]

  

I have my VP2 hooked up and running great.  My problem is that I want to send the data from the serial data logger to a laptop about 90 feet away in another part of the building.  The data logger works great when I bring the laptop to it and hook up the factory supplied cable.  Everything talks nicely.

I had my phone guy make up a 100" serial cable, plugged it in to test, and no communication.......so, two questions:

1)Davis says the limit is 40' I believe.  Anyone have practical experience exceeding this?

2) If yes to #1, what was the cable\hardware you used and how was it pinned out and with what type of connector?

Any help would be greatly appreciated!

[Bushman]

15 meters is the functional limit for serial IME.  USB can easily and cheaply exnted to 50 meters or more.  That does'nt help I know.    Serial extenders cost >$100

[Bushman]

Just  occurred to me:  switch to RS485 and you could go hundreds of meters!  The converters are 5-10 bucks.

Or the Davis Modem adpater and, well, a a modem(s). 

[SLOweather]

Make sure that the cable is made correctly. There are handshaking jumpers in the blue Davis DB-9/modular adapter.

The best way to extend the cable is to use a 4 wire cable, modular jack, and modular plug wired straight through.Then install the Davis plug on the computer end.

I have a VP2 Plus running at least 70 or 80 feet to the computer over plain 4 wire serial patched over 4 different cables with no problems.

As stated, RS232 should be good for at least 50 feet per the spec, but under proper conditions, it will go a lot farther. I have a 100' serial cable made from a flat mod cable and DB9 adapters that works fine.

Mebbe I'll try inserting it in the Davis line and see if it still works.

 

[tomcj2]

I ran about 70 feet of Cat 5 from my kitchen, where my console is, to my computer room.  I installed a normal 4 wire telephone plate in the kitchen.  The male plug on the data logger is a little bit narrower than a normal phone jack, I believe it is what they use for hand sets.  Despite the difference in width, the data logger fits in ok, and makes a good connection.  In the computer room I was concerned that somebody might plug the jumper from the computer into a normal phone jack that has 50 volt DC.  To safeguard against that possibility I installed a CAT 5, 8 conductor receptacle in the wall, and  split the pairs  and wired the jumper accordingly.  I have been using this setup for almost 2 years and have had no problems

[jruys]

The best way to extend the cable is to use a 4 wire cable, modular jack, and modular plug wired straight through.Then install the Davis plug on the computer end.

The key is as SLOweather states, the cable must be straight through.  Most normal phone lines cross the wires, at each end.  Just make sure you tell whoever made your cable that each end needs to be the same.

[deepskyridge]

You did not say if your station is wirless or cabled. If it's wireless you can use a weather envoy at your computer and not have to run long cables that will most likely be problematic anyway. I have my station setup this way and It works great.

Good Luck
Gary

[Garth Bock]

There are many ways to extend a serial cable. While a long run might work but the added resistance might cause data losses. Using a true cable extender is better. However if your VPro is wireless the Envoy is a nice addition. My weather computer can be moved anyplace in the house I want to because of the Envoy and a Belkin N+ wifi card.

[MichiganWX]

For clarification, my weather station is wired.

I'm not sure I'm following all the responses.  It appears that some have had success with using a longer than 50" plain vanilla serial cable, although their is the potential for data loss.  It appears it must be wired straight thru.

The other suggestion is to use Cat5 cable for the long run with an adapter on either end.  Sounds inexpensive.  Am I understanding correctly that this solution needs no powered "serial extender".  The powered extenders or repeaters cost around $100+ and I'm not anxious to spend more money than necessary.

 

[SLOweather]

Yup. You can do that.

Just keep track of the colors end to end so that they wind up matching color for color. Use one CAT5 pair for red/green, and one pair for yellow/black.

And, as I mentioned, use the Davis connector to connect to the computer.

An easy way to do that would be to cut the Davis cable in half, and splice the CAT5 into the middle. That's an easy way to make sure the colors match up.

[racenet]

Or just buy a telephone extension cable. That is what I use. It is about 50' in length and works fine.



Bob

[dalecoy]

 

I have my VP2 hooked up and running great.  My problem is that I want to send the data from the serial data logger to a laptop about 90 feet away in another part of the building.  The data logger works great when I bring the laptop to it and hook up the factory supplied cable.  Everything talks nicely.

I had my phone guy make up a 100" serial cable, plugged it in to test, and no communication.......so, two questions:

1)Davis says the limit is 40' I believe.  Anyone have practical experience exceeding this?

2) If yes to #1, what was the cable\hardware you used and how was it pinned out and with what type of connector?

Any help would be greatly appreciated!

The serial (rs-232) specification is conservative, and lists (approx.) 50 feet at the maximum bit rate (approx. 20 Kb).  Davis uses a slower bit rate, and that coupled with the conservative nature of the specification makes it very practical to go to 100 ft. or more.  I've done that with both VP1 and VP2 units.

I normally do the following:

[Vantage]====================[Jack]=========================[Computer]
               Davis-supplied cable                    Home-made cable

This avoids the problem of connector type, and makes it easy to get the wiring right.

The Jack is a standard "wall-mount telephone jack" available at RS, Home Depot, etc.  It has screw terminals for wires on the back (usually labeled for color coding).  The Davis cable is plugged into the front.

Now, take a regular telephone extension cable, cut off one end, strip those wires, and attach them to the correct terminals (by color) on the back of the jack.  Plug the other end into the Davis computer adapter.  See if that works.   If it doesn't work, then swap the red-green wire pair, and also swap the yellow-black wire pair.  That will now work.

[MichiganWX]

   Thank you everyone who responded to my query.  I re-examined my long cable and simply reattached one of the ends so it was wired the proper way (straight thru) and everything works fine!!

Now I can focus on deciding which weather software to use (WeatherLink or VWS) and then get it up on our website.  Guess I'll cruise over to one of the software bulletin boards.

I just recorded a 51 mph wind gust too.  That's northern Michigan for you.