Topic: Extend the 6-pole cable for the temperature sensor

[mihec]

Hi,
after months of comparison I conclude that temperature recorded in the original non-FARS Davis shield is higher for about 1-1.5 degC at solar noon but also higher in cloudy conditions. My reference is a 1-wire (actually 2 sensors) temperature sensor in a nearby Stevenson screen.

I wanted to move the temperature sensor from the Vantage Pro2 into the Stevenson screen but my homemade extension cable did not work.  I used an 8-pole (RJ-45) connector block and plugged the 6-pole connector on both sides ( sensor --> RJ-45 block --> ISS )

Is it even possible to extend the cable? I need a couple of meters, preferably up to 10m. I want to use my existing Stevenson screen and avoid buying a relatively expensive FARS.

Thanks.

[mcrossley]

IC2 cables are normally short distance, 2m or less. I believe you can go quite a bit longer but you need to pick the cable carefully to avoid capacitance issues. No twisted pairs and limited shielding are probably the way to go.

I know the SHT sensors Davis use are not IC2, but the electrical interface is the same I believe.

[Mattk]

The RJ45 connector sounds like a cross-over, you could need a straight through version?

The other thing is your extension cable could be crossed over to begin with?

[Bashy]

Just use ya phone camera or a magnifying glass to look at both connectors, check to make sure all the colours line up both ends and line up with the original temp cable. When i extended the rain bucket and the UV and Solar sensors, I am sure I used the cable from Davis, i am also quite sure i have to add new connectors for at least the solar and UV, to be honest i cannot remember 100% as it was a while ago now but i am quite certain it was the davis extension cable i used and i am sure i had to be mindful as to what the wires were doing and that some were only 6 core, just cant remember now sorry. Deffo double check to make sure all your colours line up, both ends and from the original cable, i found it easier to write it down, i drew a small diagram of the original connector and lettered each colour to the connector and the same with the new cable. I just found it easier  is all as i get confused easily lol

[mihec]

Thanks, not a native English speaker so I cannot explain the "RJ-45 block" better. It is basically a block with RJ-45 on both sides and the wires are "through". I don't think they're crossed, but I'll verify with an Ohmmeter. I hesitate to cut the original connector and solder an extension cable since this is almost irreversible thing I'm mostly afraid the length of the cable does matter here that's why I asked. I think the extra temperature sensors come with longer cable? I'll try to find more from Davis, if they reply.

[Mattk]

Standard VP2 Temp/Humidity sensor/s typical come with a 2 feet cable. there is also a longer cabled version of the Temp/Humidity combo available with a 25 foot cable, 25 feet is the Maximum cable length and probably why Davis doesn't make any 6 core extension cables. 

[davidmc36]

If you do any customization work more than once it is worth it to get the Cutter/Stripper/Crimper tool, some connectors and a bit of flat wire.


Make needed cables from original material, just long enough, but not excessive.

[Phil23]

IC2 cables are normally short distance, 2m or less.

Yes, and 2 metres is really making a stretch with everything in your favour.
I do wonder how much luck you could have with some type of active extender or repeater.

The simplest of searches shows a few devices like this https://www.google.com/search?q=PCA9515A

Maybe a a few of them alone the line could extend to a reasonable distance.

(During my time on the Steel Works in the '80's we built similar things to extent RS232 at 300 Baud. They existed about every 50-100m).

Edit:- Scrap that, two or more cannot be placed in series as per the data sheet.

https://html.alldatasheet.com/html-pdf/107978/PHILIPS/PCA9515A/596/2/PCA9515A.html

[jerryg]

I have had no problem extending the sensor cable up to 50 feet with cat 5 cable and a cat splice.

[Monto Weather Qld Australia]

This is what I did to make use of a stevenson screen.