Stumped on Communication Issues - We think it is/was our radio. Details are inside.

[SagesOfRPG]

We recently competed in our first competition and we had some communication issues with our robot. We would do autonomous, and then get into teleop then about a minute in we lose connection our robot light goes solid and we are dead in the water.

We had really helpful orange and yellow hats that helped us throughout the compeition but we never quite figured out the problem, until right before our last match we had two revelations.

One was that we put in a new ethernet cable and it seemed to communicate beter. Next was the big one. We could knock lightly on our radio and it would lose connection. We would get connection back but it did not seem that that worked when on the field.

We got a loaner radio and we could not replicate the knock test that would make us lose connection.

We are looking for help trouble shooting this issue as we would have done better in matches if we were able to stay on for the whole round. The 1 or 2 matched we stayed on for the entire time we did really well.

I can provide more information on anything that is needed so we can see if we can figure it out.

Other things we though our communication issues would be were:

• CPU on classmate laptop - tried 3 laptops and ruled this out
• CPU on roboRIO - Looked at logs and it seems like it should not be the issue.
• Programming issue in java that was creating a load on the roboRIO CPU - we looked at the code with 3 or 4 teams and officals and did not see anythign that could have caused it. The only thing that we had "checking" frequently was an ultra sonic sensor that we were not using so we commented it out.
• Battery connections - we checked and recrimped things as well as used other teams batteries and ruled this mostly out but we are double checking all connectors etc.
• Lose wires - checked and wiggle tested everything. Took any lose wire out and re tightened them.
• Radio that rebooted when we knocked on it - replaced with new radio that passed the "knock test"

We did walk away 23/40 and winning Rookie All Star. So we are super proud of what we did. Just would love to figure it out.

Thanks in advance!

[FrankJ]

If knocking the radio makes you lose the connection, your problem is with your radio. You might might other problems as well, but you still have a problem with the radio.

The two things that come to mind it power & physical such as a cracked board or bad solder joint. Make sure you power connector is tight and the wires have adequate strain relief. Tape or hot glue can be used to keep the connection tight. The radio is meant to be attached to a relatively stable building not a robot. Rigidly attaching it to the robot transmits a lot of shock load.

[Pault]

Sounds like it was just a bad radio. I don't think that you need to do anything more.

Just to be safe, however, one thing that I noticed you didn't include on your list is strain relief on all your wires. One of the things I really dislike about the current control system is how all critical power goes through those finicky weid-muller connectors. If you just zip tie down the wires near the connectors such that someone tugging on it further down the line doesn't put any strain on the connection itself, you will have a much more reliable system. Also definitely do this on barrel connector for the radio itself. Those things were designed to come out easily.

[SagesOfRPG]

Originally Posted by Pault

Sounds like it was just a bad radio. I don't think that you need to do anything more.

Just to be safe, however, one thing that I noticed you didn't include on your list is strain relief on all your wires. One of the things I really dislike about the current control system is how all critical power goes through those finicky weid-muller connectors. If you just zip tie down the wires near the connectors such that someone tugging on it further down the line doesn't put any strain on the connection itself, you will have a much more reliable system. Also definitely do this on barrel connector for the radio itself. Those things were designed to come out easily.

We made sure all wire are strain relief to the best of our ability. Also we taped and ziptied everything in so we made sure it wont come out.

Originally Posted by FrankJ

If knocking the radio makes you lose the connection, your problem is with your radio. You might might other problems as well, but you still have a problem with the radio.

The two things that come to mind it power & physical such as a cracked board or bad solder joint. Make sure you power connector is tight and the wires have adequate strain relief. Tape or hot glue can be used to keep the connection tight. The radio is meant to be attached to a relatively stable building not a robot. Rigidly attaching it to the robot transmits a lot of shock load.

Got it! We also added in some pool noodle to absorb some of the shock if we get hit or take a big jump. We have the power connector in with a zip tie and tape :-)

[Greg McKaskle]

If you will post a log file or two where your issue presented itself, I'll be happy to see what its info supports. I completely agree with Frank that your radio should not do that and is at least one of your issues. As you well know, the robots are not one-trick ponies, and there are plenty of opportunities for Murphy to introduce himself and provide you with a problem to solve at the actual event.

To the comment on the Weidmuller connectors, I've CSA-ed two events already this season, and plenty last season, and the connectors that are almost always causing "connection" problems are nuts and bolts and sometimes barrel connectors.

About 70% of the robots that lose power are due to the battery terminal connections or the main breaker connection (nuts and bolts). The input to the PDP is far less common, but I see loose ones at each event. The radio barrel jacks are probably next on the list and sound more like this robot, where the RSL never goes out, but the robot is waiting on its radio. Next are stray wires causing a short at any of the Weidmuller or the roboRIO screw terminals. Next is a wire being pulled out of the screw terminal, and finally, are wires fraying and/or breaking at the Weidmuller connection. I totally agree with your input on wire management and strain relief, but I'm not sure what aspect causes you to call them finicky?

By the way, some of those connectors are made by Wago.

Greg McKaskle

[SagesOfRPG]

Originally Posted by Greg McKaskle

If you will post a log file or two where your issue presented itself, I'll be happy to see what its info supports.

Thanks! Where do I find the files on the machine to copy to you. I know how to view them but not sure how to find them to send along.

I am hoping that the major issue was just a radio one.

[nuclearnerd]

We have a similar problem with both of our radios, but only on one port each! If yours is the same, try plugging your Ethernet cable into the other one.

This is a really frustrating behaviour. I feel like we deserve a refund, but can't afford the time to return ours.

[Greg McKaskle]

The path to the logs is shown in the path control beneath the list whenever you open the log file viewer. This would allow you to swap folders in case you want to look at some from 2015 that you moved out of the way, or ones from another laptop that was used as a DS for awhile.

Anyway, the logs are stored in C:\Users\Public\Documents\FRC\Log Files. This looks slightly different in the file explorer versus the command line, by the way.

They are a collection of .dslog and .dsevent pairs. Ideally, post both types of the file since they contain unique info about the match.

Greg McKaskle

[Pault]

Originally Posted by Greg McKaskle

If you will post a log file or two where your issue presented itself, I'll be happy to see what its info supports. I completely agree with Frank that your radio should not do that and is at least one of your issues. As you well know, the robots are not one-trick ponies, and there are plenty of opportunities for Murphy to introduce himself and provide you with a problem to solve at the actual event.

To the comment on the Weidmuller connectors, I've CSA-ed two events already this season, and plenty last season, and the connectors that are almost always causing "connection" problems are nuts and bolts and sometimes barrel connectors.

About 70% of the robots that lose power are due to the battery terminal connections or the main breaker connection (nuts and bolts). The input to the PDP is far less common, but I see loose ones at each event. The radio barrel jacks are probably next on the list and sound more like this robot, where the RSL never goes out, but the robot is waiting on its radio. Next are stray wires causing a short at any of the Weidmuller or the roboRIO screw terminals. Next is a wire being pulled out of the screw terminal, and finally, are wires fraying and/or breaking at the Weidmuller connection. I totally agree with your input on wire management and strain relief, but I'm not sure what aspect causes you to call them finicky?

By the way, some of those connectors are made by Wago.

Greg McKaskle

I find that, if done properly, their connections generally hold, but it is very easy for them to not catch on and fall out. It is also hard to figure out how much to strip the wires, because often times it helps to do it excessively and bunch up the wire inside, but that results in bare wire sticking out that can caused shorts.

Over the past 2 years I have seen 2 connections fail from them. One was very clearly a bad connection from the beginning because it was a thin wire, but thankfully it wasn't very important to our robots functionality. The second was the wire to our compressor, and we don't think that it was inserted poorly, but we aren't sure.

In the end, I wouldn't mind using those connectors for non-essential components. However, I would feel a lot more comfortable if the roborio and radio were powered by terminals clamped by screws or something similar rather than a connector that averages about 3-5 failed pull tests before we finally get a reliable connection. The fact that you haven't seen many failed Weidmullers puts my mind at ease; maybe I am just underestimating how many teams properly test all their wiring.

[Greg McKaskle]

https://wpilib.screenstepslive.com/s...control-system

That page includes some info on both Wago and Weidmuller including length to strip. I've also seen a number of teams using a ferrule successfully. Thanks for the details.

Greg McKaskle