Re: Intermittent connection on field only
 

I think I've noticed a pattern in who these failures happen to.

They're ALL using LabVIEW... Has there been a single failure of this type with a C++ or Java team?

Re: Intermittent connection on field only
 

Your symptoms do point to the radio power dropping out momentarily. If you reconnect after 40 seconds then the power to the radio was interrupted.

Replacing the radio and converter are a good start, but don't overlook the Power Distribution Board. Also, check the connection to the barrel plug on the D-Link. (Many teams use hot glue, tape, etc to ensure a somewhat better connection).

I am wondering if PWBs in the radios are being damaged internally this year due to the harder shocks that robots are taking (falling off the bridge, going over the bump). The D-link radios were designed to sit on a desk, not to take high-G impacts. Might be worth it to make sure the radio isn't rigidly mounted to the frame.

Re: Intermittent connection on field only
 

While a DAP-1522's expected link-up time is 50+ seconds after a reset, 40 seconds is almost exactly right for communication to be reestablished after a cRIO reset.

I watched one D-Link DAP-1522 consistently work in less than 30 seconds after a complete power cycle of the robot. It was, to put it mildly, unexpectedly quick. This was not using wireless, but it's still faster than I generally see with a wired connection.

Re: Intermittent connection on field only
 

We're running Java and had the same problem multiple times at the Oregon Regional. Other teams were having problems as well.

Re: Intermittent connection on field only
 

I was FTAA at the regional at Utah this last week, and we were having similar problems. The FTA found that every team on the field had high trip times (>30ms) when there was a team with a D-Link running firmware version 1.4.

We has the CSA downgrade those bridges to v1.2 of the firmware and all of the trip times went back down to normal. I am not sure if this is the same problem that everyone else was having, but downgrading the firmware on any of the older bridges running 1.4 seemed to help.

-Clint

Re: Intermittent connection on field only
 

I hope FRC ensures that every robot on the field is running v1.2 going forward.

Re: Intermittent connection on field only
 

I am sure that the FTAs and FIRST staff will look into this and, hopefully, we will see a response from them at the next events.

Re: Intermittent connection on field only
 

We also had this issue at the LA regional, and were advised that there was a "general issue with the field" by the FTA. I was informed that it was causing control problems and sending reset commands to robots.

I'm not sure if this was the cause, but I think it may explain some of the problems that occurred to various teams, including 2637.

Re: Intermittent connection on field only
 

Our team at Sacramento/Davis coded in C++ and we had this problem.

The odd part was that we were only hit by dropped packets on Saturday. Team 3256 was also hit by this however they might have fixed it by halving the resolution on both of their cameras.

Re: Intermittent connection on field only
 

We had a problem at VCU where we would lose comms during the match, and the cycle time was about 40 seconds so we blamed the cRIO rebooting but couldn't figure it out. No problems showed up when tethered in the pits, and couldn't get a slot on the practice field. It turned out to be that the radio was not connected to the regulated supply on the PD board and was cycling when voltage dropped. This was noticed by our FTA who was able to watch the robot from a close vantage point and saw the radio reboot.

We had a handful of problems plauge us throughout Friday, but they were all traced to robot issues and not FMS. (bad jag, bad motor, improper wiring)

Wetzel

Re: Intermittent connection on field only
 

We had issues last year with the D-Link disconnecting. We competed in two regionals before tracing it to the barrel plug, which we purchased from Radio Shack. The ID of this Barrel plug was slightly larger than the AC adapter cord that came with the D-Link. We changed the Barrel plug, using the one that came with the D-Link and the problem went away.

Re: Intermittent connection on field only
 

I actually had an oscilloscope at the MAR Mount Olive District event and someone took the time to check the power on a teams robot that was experiencing these symptoms. This was a 25Mhz analog scope and there were no issues.

Immediately I suggested it could be the camera feed, but it seemed like the other teams who were helping them were using it with better success. I also suggested it could be the CAN bus or somehow related to an interaction with the CAN bridge in the Jaguar....not to toss any blame on the Jaguars...I was merely speculating.

They were using LabView. We don't use LabView and I am not clear on how LabView handles exotic exception situations during communications.

When they turned off their video (which was a serious handicap for them) they could reliably control their robot on the field. As soon as they started using it again they had problems again.

I would like to point out, that I was told our field was apparently configured with 802.11G and everything was sitting on channel 6. I was told that's how it was setup and we all had to deal with it (even Team 11 and we were the host). That would mean that the most you can hope for is 54Mbps. However, with distance, interference, TCP/IP loading issues (it's a reliable protocol and if you don't understand the implications do some research or this will get too complicated to follow) you don't really have 54Mbps.

If what I was told was correct, this is going to be a problem if your robot is bandwidth hungry.

Re: Intermittent connection on field only
 

Yup, our teams runs a javabot, and we had the same problem during our practice matches. Our problem was that there were a few inappropriately handled errors and too many output statements causing major peaks in our cRIO's CPU usage. Having a robot project where the loop iterates as fast as possible can also drive up that CPU usage.

Re: Intermittent connection on field only
 

It wasn't. The field setup uses 5GHz as you can see with a 5GHz NIC or by looking at your radio setup after programming.

Re: Intermittent connection on field only
 

The one field I have seen up close had all the robot networks on channel 60, not 6.