conext scp wire length?

mmag · August 2013

Does any one know why the wire length for the schneider electric conext scp cannot exceed 130 feet?(thats what it says in the instructions) and is there anyone who has tried longer?

NorthGuy · August 2013

Re: conext scp wire length?

I searched and I found this. They also have a link to PDF document TI dicument which contains a lot of details.

Xantrex uses 250kbps, so at this speed it should be ok to at least 500-600 ft. Because of the wire resistance, they suggest increasing the terminal resistors. As an easy hack you can simply pull one of the terminators out, which will double the resistance, but generally this is not a good thing. It's best to make your own terminators with bigger resistors. You can also use thicker wire to decrease its resistance.

The other problem that you may encounter is power. SCP is said to consum 800mA (if I recall correctly). CAT5 cable is probably #24AWG, so 130 feet back and forth will give you 10 Ohm resistance, or 8V voltage drop, which leaves only 7V from their original 15V. If you go further, it'll be not enough voltage for it to operate. I guess it needs at least 5V, may be more. For this, you can again go with thicker wire, or you can provide a separate isolated power source for the SCP.

In short, you can go longer, but it may not be straightforward.

NorthGuy · August 2013

Re: conext scp wire length?

Actually, I was wrong about the power. By Xantrex docs, SCP only consumes 200mA, and Xanbus actually uses three pairs of wire for power, so at 130 ft the resistance will be only 3.3 Ohms and voltage drop will be only 0.66V - very good actually. Even at 500 ft, resistance will be 13 Ohm, and voltage drop only 2.6V - not great, but may work.

mmag · August 2013

Re: conext scp wire length?

Thanks for the response NorthGuy, i am trying to run a length of 250' to my house from my power shed, sounds like i should just give it a try and see what happens

NorthGuy · August 2013

Re: conext scp wire length?

That's the best way. If you haven't bought the cable yet, try to buy a cable with thicker wires. The wire gauge should be on the jacket. If you find #22AWG, that's the best. CAT6 may have thicker wires than CAT5. Let us know how it turned out.

mike95490 · August 2013

Re: conext scp wire length?

mmag wrote: »

Thanks for the response NorthGuy, i am trying to run a length of 250' to my house from my power shed, sounds like i should just give it a try and see what happens

Do a single run, no splices or connections. And 22ga cable, avoid 26 or 24ga.

Joe_B · August 2013

Re: conext scp wire length?

If voltage drop turns out not to be the limiting factor, it might be timing. If you have issues with the length of the run, try lowering the signalling rate to 125 KBPS.

vtmaps · August 2013

Re: conext scp wire length?

mmag wrote: »

i am trying to run a length of 250' to my house from my power shed, sounds like i should just give it a try and see what happens

One more thing... don't put that cable in the same conduit with your AC power cables. --vtMaps

mmag · September 2013

Re: conext scp wire length?

update used 24 gauge cat5 in a seperate conduit and it did not work, there was power at the scp but no data from the cc, should have listened and got bigger cable but thats what we were using for my magnum remote so thats what i already had purchased, now i am going to try bigger cable outside of the conduit first before i invest any more time

NorthGuy · September 2013

Re: conext scp wire length?

mmag wrote: »

update used 24 gauge cat5 in a seperate conduit and it did not work, there was power at the scp but no data from the cc, should have listened and got bigger cable but thats what we were using for my magnum remote so thats what i already had purchased, now i am going to try bigger cable outside of the conduit first before i invest any more time

Before you buy a new cable, I would try few things:

1. Try connecting SCP with a short cable to see if it works. There could be a problem elsewhere.

2. Still with short cable, try pulling one of the terminators. See if it works. Put it back, then pull the other one. Make sure it still works.

3. With long cable, try pulling out one of the terminators. If it still doesn't work, put the terminator back, then pull the other one and see if it works. If it does work, this is not a good way to run it permanently, but might give you an idea how to fix it.

mmag · September 2013

Re: conext scp wire length?

the scp works in my power shed with a short cable but not in my house with the longer wire, can you please explain how to pull the one of the terminators, thanks

NorthGuy · September 2013

Re: conext scp wire length?

mmag wrote: »

the scp works in my power shed with a short cable but not in my house with the longer wire, can you please explain how to pull the one of the terminators, thanks

Your network configuration should have terminators at both ends. They are little black things that you insert in the connector next to the cable. You just remove it out, so that it is no longer connected. So, instead of two terminators you now have one. This increases resistance, which may help with longer wires. Don't remove both terminators at the same time.

mmag · September 2013

Re: conext scp wire length?

thanks i will try that today, if it works why is it not good to use it like that permanently?

NorthGuy · September 2013

Re: conext scp wire length?

mmag wrote: »

thanks i will try that today, if it works why is it not good to use it like that permanently?

You're supposed to have terminators at both ends. The problem might be that the stock terminators are too small for the length of the wire that you use. Then you will need to make your own with bigger resistors.

If running with one terminator works, this will tell you that this is the problem you need to fix. But it's not good as a permanent solution because the network is designed for two terminators, and running it lobsided may not be good for the components.

BB. · September 2013

Re: conext scp wire length?

In general, terminators should be sized to the characteristic implemented of the cable. (I.e., Cat 5 cable is around 100 ohms).

Category 5 cable

So, the effective termination resistance should be 100 ohms too.

Terminators are there to prevent electrical reflections at the end of the cables. If you remove a terminator, it may give you better signal level, but with "echos" mixed in... Usually not a great solution.

In theory, the length of the cable does not affect the "loading" of the drivers or terminators. What happens instead is that the pure resistance of the long (and thin) copper wire causes your (for example) 1 volt signal at the driver to be less than 0.1 volts a hundred yards or so away. While removing or changing the terminator type/value can help a little bit... It may end up causing data errors over time (hot weather, higher cable resistance, water table in ground lowers cable impedance, etc.).

Your might also double check with an ohm meter (or Cat cable tester) that the connector pairs are correctly wired out and that your don't have a broken connection (Cat 5 cables are twisted in pairs and mixing up the A and B signal wires between twisted pairs can cause crosstalk on longer cable runs. Similarly, a short cable run with one broken signal connection may still work while a longer run does not--assuming differential signalling).

-Bill

ChrisOlson · September 2013

Re: conext scp wire length?

There is another option now with the Conext ComBox that will eliminate running a long Cat5 for remote SCP. You can install the ComBox in the utility room and use a powerline ethernet adapter to network it with the house network. I bought a Linksys one from OfficeMax so I could have internet in my shop that is on a 250 foot underground AC wire run. It works fine and I get 100+ Mbps connection in my shop now thru the AC wires to the network in our house.

Then you can use a little Android tablet computer in the house. The Android tablet running the free ComBox App in it, with the ComBox, completely replaces the old SCP and gives you WAAY more information about the system than the old SCP did. We have our little Samsung Galaxy Tab2 7.0 Android tablet computer on the microwave on a little stand, and it is now our SCP in the house that we use to interact with our power system.

The tablet computer is connected to our wireless in the house, which is in turn hooked to the wired ethernet that the ComBox is hooked to. I can take my laptop out in the shop where I can't get a wireless signal, plug it into the Linksys Powerline AV adapter and access the ComBox with my web browser from in the shop thru the underground AC wires. It works fine on a 250 foot run as long as the Powerline adapters are on the same circuit on both ends.

--
Chris

conext scp wire length?

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