Lon link resistors?

[scrooloose]

I have always been taught that you need resistors at the end of the link, size depending on what gauge wire you use, 105ohm for 22g, etc..

I was on a job today with Invensys and they have a full link with a repeater with no EOL resistors. The link scanned good, so obviously it works.

So my question is, does the link requirements depend on manufacture or type of repeater or ...

[freddy-b]

Its a hit or miss thing...I dont know the science behind it, I have seen networks cruise along fine... others fine for months then start flaking out, then be ok again and so on and so forth.

So the safe bet is to wire to the Echelon standard .. from the beginning when the layout is fresh in your head...and not take the chance.

[Chris_Worthington]

This is a good question for Sysint, but I believe a lot of repeater/routers have internal resistors?

This may be wrong, but I never install EOL until after scanning the bus without EOL, no errors no EOL.........

[lontshooter]

The first thig to ask is what type of network are you using a BUS or STAR type.
I only use 1 Terminator on a network at the farhtest point unless the distance between the farhtest point are about the same distance.
Most Router have an internal resistor and that acts as a EOL, but you may need to add one in another location.
There are guides in Echelon books that will advise you on the right procdures to follow and when to use them.
I have found on large networks that they are a benefit to keep the signal strong and erros low.

Lontshooter

[sysint]

For FT in LON this means Free Topology so the termination values can be different dependent on the physical wiring. Loytec actually has a Termination product (L-Term) for this.

[dapper]

I was curious once and checked a network (free topology) with a protocol scanner that had about 1-3% error rate. I removed the EOL to see the effect. The error rate jumped to 80-90%.
That convinced me to always use the EOL.

[sysint]

that's sounds extreme, but many guys see it the other way: I seem to get away with no termination so I'm not going to do it...

It is very easy to get lazy with comm wiring with CEA-709 as opposed to other fieldbus technologies because it handles alot of issues. However, it's better just to do things properly the first time.

[davetec]

Here we go again. Echelon provides wiring guidelines including terminating resistor usage for a reason.

I have seen many occasions where comms to one device on a test bench network was unreliable until a terminating resistor was installed. Dapper hit the nail on the head, proper termination makes a big difference.

[zandman]

What software does everyone use to scan the LON bus?

Zandman

[sysint]

That's obvious for me... actually I have two different.

[scrooloose]

Is there a free program out there that will show link errors? Like the NLutil or if it cost is there a cheap one? I would simply need it to shows link errors.

[lontshooter]

You can download from Echelon the Lon scanner and use it in demo mode, there are restriction in the read me file but I have had to do it once on a customers computer, because I normally connect up with my laptop and use the full version that I have installed.

It will give you the idea of potential issue in the network.

[sysint]

Is there a free program out there that will show link errors? Like the NLutil or if it cost is there a cheap one? I would simply need it to shows link errors.

LSD Tool Loytec. You can download it. Works with Loytec NICs.

[digo]

Is there a free program out there that will show link errors? Like the NLutil or if it cost is there a cheap one? I would simply need it to shows link errors.

In AX, it's built-in.
Lon Utilities Manager -> Local Lon Device -> Reports -> Transmit Errors No Clear -> Execute

You can also use this on a learned network managed by others - just don't commission or bind anything.