Limelight Cutting in and Out


We noticed that during some of our matches recently, the limelight connection would repeatedly cut out for a few seconds. We are currently running the limelight off of a network switch that is powered from the VRM and connected to the radio with the Rio being ran on the radio’s primary port. We initially needed the switch since we were going to add another camera and we wanted to avoid the second port on the radio as we heard it is not reliable. At this point we are unsure if the problem is with the second port of the radio being finicky and messing with our communication with the Limelight or if it is due to the network switch (whether it be power or connection)

Thank you


We have a single network switch plugged into the first radio port, nothing in the second radio port, and the RoboRIO and Limelight both plugged into the switch.

The limelight was cutting in and out on us all day at our Saturday competition. So I don’t think it’s the second radio port that’s your problem. According to marshall, that problem manifests itself as the device in the 2nd port simply not connecting to the network when you power up the robot.

We have a second HD-3000 “driver cam” plugged into the limelight USB port. Both the limelight image and the driver cam stream to our dashboard side by side.

Do you have a driver cam plugged into the limelight USB port? Another thread on here suggested this was the root cause of the limelight cutting in and out, and suggested installing PhotonVision on the limelight as a work-around.

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We had this issue in Idaho. We had a long cable run for the power to the limelight which causes a voltage sag and brownouts. Switching to some thicker wire fixed this issue.

That’s interesting. Their documentation would suggest it’s designed to run down to 6V, and I don’t recall seeing it go that low in our logs:

We have ours connected with 18 AWG wire. What gauge did you change to?

EDIT: also, we’ve observed this problem while the robot isn’t enabled and isn’t drawing large amounts of current.

We are also having this issue pretty regularly, and are actively trying to fix it. We don’t think it is power related since our limelight does not seem to be doing its reboot sequence. This seems to be a short loss of data (like maybe 5 seconds) then it’s back. We are getting this issue randomly, but it is very frequently. We are getting it ~ once a minute.

Originally we had the limelight plugged into the 2nd port on the Radio.

On Saturday we decided to instead go with the switch solution that Marshall and team 900 suggested, and we now have the Rio and Limelight both on a network switch, and then go out to the radio.

We will see if this fixes our issue. We were originally going to plug a USB camera into the Limelight, but have decided not to with all the other issues that are reported.


We had occasional/random issues with limelight disconnects both short (up to 5 seconds) and longer (never came back) while our limelight was plugged into the 2nd port on the radio.

No issues through a full regional now since installing a network switch and connecting the RIO and Limelight to port 1 only. (we also hot glued the ethernet cable for good measure but all data points to the switch as the fix.)

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I should say that I wasn’t actually there, just helped fix the issue remotely.

We ended up changing to 18 AWG wire. Not sure what we started with. We also switched to using the power port from the POE and changed our ethernet cable. Radio port didn’t make a difference.

We never had the lights go out or the limelight reboot, it would just lose network connectivity. We also removed our network switch, but the team is conflicted on whether that was the issue or not.

I don’t think we had the same issue then. We were working fine in the pits and while disabled on the field. Just when driving around, we were having the issues.

Your setup wasn’t completely described and might vary from the LL documentation and best practices described in various threads here on CD. We use a new LL 2; that may differ from LL 1.

Don’t power a LL 2 from a regulated power supply. The students keep thinking more regulators are good and insisted on connecting the BrainBox and the LL to a VRM. That isn’t right! One regulator per power circuit to a device, please, and the BrainBox and LL already have that one regulator builtin.

This year we used the radio primary Ethernet port for the BrainBox switch and everything else goes into the BrainBox. First year we didn’t have comm problems.

The LL 2 document warns of comm disconnects; even the image previewer in the LL config program hangs! We tried the browser interface they say not to use and indeed it disconnects randomly within seconds to minutes. They warned us! Auto reconnection software is required as they stated. We use the WPILib ShuffleBoard and that does reconnect fairly quickly.

We used the LL USB port for a driver cam without incident.

We used the LL 2 POE feature and only once did the LL 2 fail with power off and wiggling a wiring connector revived it. We know what that problem was! (Does anyone know how to inspire kids to think making good crimps is fun?)

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