Puzzling comm / latency issue with Roborio and D-Link over wifi

[jwhite]

We've got an odd behavior that has us puzzled.

We're deploying Java, and everything seems to work.

However, if we look at the log viewer, we see a periodic (about every 8 seconds) drop in communication quality (we get a nice blocky yellow graph). Further, if we start a ping on a terminal, we see 2 ms for most pings, and then about every 8 seconds, we get a ping time of 50 ms.

Again, everything seems to work, but it is puzzling.

And if we wire directly in to either the RoboRio or the D-link with an ethernet cable, the problem vanishes.

Has anyone else seen anything like this?

Cheers,

Jeremy

[Greg McKaskle]

So if I understand correctly, you have a wifi glitch every eight seconds. Your comms are fine over net.

One thing to check when the glitch is that quick is to see if an update service is running at that moment. I believe another post indicated that an AutoDesk update service was causing something similar.

Another thing to check is to look at the laptop drivers for wifi and see if newer ones exist. And you can also try with a different laptop and that may help isolate the problem to either the laptop settings or the DLink settings. There is also the possibility that other APs are causing this. What type of wifi environment are you in?

Greg McKaskle

[jwhite]

Originally Posted by Greg McKaskle

So if I understand correctly, you have a wifi glitch every eight seconds. Your comms are fine over net.

One thing to check when the glitch is that quick is to see if an update service is running at that moment. I believe another post indicated that an AutoDesk update service was causing something similar.

Greg McKaskle

Sure enough; AutoDesk Application Manager. Tell that *not* to start at Windows start time (or kill it), and everything becomes rational.

Thanks for the pointer!

Cheers,

Jeremy

[darkorbit]

We were having this same exact issue. We are programming in Java, DS Version 17121400 and the 09021500. We've updated all firmwares including using different laptops, but we keep seeing the same disconnect issue.

Here is what our DS is showing:

We've tried switching out the AP and checking for channel interferences. It's not a power issue for us. The AP always has blue lights. As stated by the OP, if we tethered via network cable, all is well.

In another post somewhere I read that update services on the computer could cause the disconnect, but that is not the case for us since I disabled all update services/startup programs on the laptops.

After reading these common posts about this issue, I concluded that maybe windows 8 was the problem since we tried the ds on 3 different windows 8.1 x64 laptops with java 1.8 x64 with the same result. Our last test (before we called it quits...at 5am ) was putting the DS on our windows 7 laptop and hoora! no more wifi disconnects?!...

I'm not sure, and cannot confirm what the exact issue is that would be causing this problem on windows 8.1, but all we know for sure is all our comms problems went away after we switched to our windows 7 laptop.

EDIT: Based on this
http://www.chiefdelphi.com/forums/sh...d.php?t=133114
Looks like there was a new firmware for the RoboRIO:
roboRIO firmware
2.1.0f3 comes with the above FRC Update and is located here: c://Program Files/National Instruments/Shared/Firmware/cRIO/76F2/roboRIO_2.1.0f3.cfg

I couldn't find where that firmware was located until I saw that post. We'll try updating the RoboRIO and report back. Got to go shovel out my car.

EDIT:
Ok now we've updated roborio/pcm firmware, but it looks like the disconnects are even worse.

[Greg McKaskle]

I don't think there were actually firmware changes to the roboRIO, just library changes.

Anyway, it looks like you are seeing the 69sec glitch where your laptop wifi scans other channels looking to see what other access points are around. I have not personally seen this on any laptop I have access to, so I can't be too specific for how to fix it. But I have heard from others that they have improved it by downloading an installing the latest drivers for their wifi adapter.

Also, at an event, you will not be using the wifi on your laptop. You will be using ethernet and borrowing the field's wifi. So this wifi glitch, while annoying, will not affect you on the field.

Greg McKaskle