UCCNC does not execute G-code files.

[ger21]

You could try adding another network card. I'm using a $12 card I got from Ebay.

[CT63]

Try reinstalling the network driver in the device manager. Could be corrupt.

[cncdrive]

You said that the latency is at the 20msec and remains there when you running g-code, that is a problem, it should not be like that.
If the latency goes above 20msec is already a problem and if it remains there indicates that there is some real problem,
because the latency test does not measure above 20msec, so if the value is at 20msec (the very top) means that the response time can be 20msec or anything more.

You've mentioned this in your post:

CNC and desktop both running from the same UPS.
UC400ETH is powered at 24v.
Grounds tied together on the two power supplies.

And I'm wondering what these statements exactly means?
What do you mean by "grounds"?
The Protection earth (PE) or is the PC running off a DC power supply and so the 2 DC bus grounds are commoned?
Ethernet is isolated and if the second case then you break the isolation barrier doing so which could cause a ground loop and could lead to noise problems which could actually cause lost ethernet packets and could possibly rise the latency.

A latency issue like that could be caused by a power supply issue or a network card problem or by serious noise in the ethernet communication.
Or it could be caused by a too weak PC, but since you said it has an I7 core CPU I think it is probably not the reason, but you could check the CPU usage of the UCCNC.exe process in the Windows Task Manager when you run the g-code, so we could cross this possibility out quickly.

[CT63]

We've ruled out the power supply by changing to the 24v ps... same problem. A not too likely problem is there is another function running that is trying to use the network card at the same time.
At this point I would swap out the network card if reinstalling the network driver doesn't fix the problem. Unless there is something using up CPU time which can be quickly checked in the task manager.

[LBayZG]

Thank you, everyone. I wish to report the beginnings of success, the tool now works.

One of the suggestions given by CT63 was to re-install my network driver. I did that and everything started working. The latency is now something like 2 ms.

I will next start cleaning up this 'testing mess' which I have created, and then try to migrate this success onto my network.

But this is quite good enough for tonight.

[CT63]

Glad you got it working. The network drivers seems to be a weak link in Windows 7. On the bright side, look at all the experience you gained troubleshooting this problem.

[LBayZG]

I am happy to report that my homemade CNC controller is working well over my network. The network switches and router don't seem to bother it.
The network latency (about 2ms) seems to be the same as for a direct link between the two devices.

What I did was re-install my network adapter's driver (ie: the NIC driver). I did not re-install my entire networking service. The NIC driver re-install instructions that I used are here.
https://kb.wisc.edu/page.php?id=58029

One more thing. I also implemented a patch for reducing Windows' network latency.
It's supposed to disable something called the Nagle-algorithm. Doing so allows smaller (partially filled) network packets to be used, supposedly reducing network latency.
The computer's networking service does not 'wait' for additional data with which to fill up the network packets before issuing them.
I figured that this modification would be good for the continuous back and forth messages between the UC400ETH and my PC.

Here is the link to the article show how to do this.
http://www.pcadvisor.co.uk/how-to/internet/how-reduce-your-latency-in-windows-7-3427572/

Does it help? I honestly don't know. I implemented this prior to re-installing my NIC driver. So it did not seem to have any effect at the time.
But, now that re-installing the driver for my network card has fixed things, it might actually be benefitting me.

[beefy]

Terry,

do you know which motherboard that is ??

Keith

[beefy]

Hmmm, OK, noted.

I'm sure I'll figure out the make and model of motherboard with that info.

Keith.

[beefy]

No, that's fine Terry. I would have just noted the MB make/model if you'd known it off the top of your head. No need to go disassembling things. If I ever come across issues I'll just get a PCI slot network card.

Mach3 had certain motherboards that just plain didn't work, so I'd note which ones. But that was a bit different and I always used the parallel port.

Keith.