Robot looses comms when hit/jolted

[Greg McKaskle]

A couple seasons ago, this was very common. The easiest diagnostic was to time how long it took to regain power on the field, or to walk to the robot and observe the LEDs to see which devices are still powered and which are not. Finally, try if you have it narrowed down, wiggle and yank on various wires to simulate the shock of the hit. Keep in mind that it could also be a short, so look for bare wires that could be hitting anything, frayed wires, and messy wiring connections entering the cRIO or other devices.

Greg McKaskle

[jimwick]

We had the same problem and finally traced it to a loose ground. We fixed the ground and that solved it.

Jim Wick

[Mr. Rogers]

The c-Rio input wires on our practice bot have come loose, our main breaker wires have come loose, pwm's have come loose. We're in the process of hot gluing everything at the moment. Strange things happen when you pretend that your robot is the General Lee.

[Lightfoot26]

This was happening to us early on, I narrowed it to two things...
1.) I had quickly wired the DAP-1522 to the 5v converter and that into a normal 12v output on the PD board. Well those were dipping voltage as my motors stalled working their way across the bump. So I wired that up to the 12v WAGO dedicated on the front of the PD board.

..that worked for awhile and it started happening again.... SOOO

2.) I figured out that as the cRio bumped it'd lose comms.... a simple tightening up of its mounting screws, and now the bot can bump, rock and roll all it wants, I stay connected.

[Al Skierkiewicz]

Don't use hot glue. Figure out why they are coming loose. To hot glue something that is incorrectly assembled means you can't fix it when you need to. Most often when wires come loose on the Crio, it is because they were improperly striped. If the wires to not fully insert into the connector they will be pushed out when you tighten the screw on the side. If the main breaker comes loose, I have to ask if you are using the locking hardware that came with the breaker? For those items that move with the robot, find a place near the connection and use a wire tie to secure them to the robot. We loop the wire going to anything and then take it straight down to the deck. Since we use perf stock to mount everything, we simply pass a tie through the perf stock and around all the wires. The loop allows some movement, and the tie restricts the movement so that it can't be pulled off.

[Shaun Coon]

we had the same exact problem and it ended up being that the signal light had exposed wires that were hitting the 80 20. if you havent rewired the light you might want to do that.

[sand500]

Is there any reason why not to use the 5 volt wago connector on the PD board for the radio and connect the camera with the 12V to 5V connector?

How can you tell if the problem is a Radio reset or a CRIO reset.

[iambujo]

We had this same problem today when trying to go over the bridge. We reproduced it by dropping the front the robot an inch or 2 against the floor. We then focused in on the cRIO. We shook it (a bit violently) and the 'Communication' and 'Robot Code' both went red on the driver's station.

We tightened down the cRIO, pulled out the modules, vacuumed it out, reseated them and tightened down the Digital ribbon cable. After doing all these it never happened again. If we had more time we would have tried one thing at a time since it would have been nice to know which it really was, but you know how it goes at crunch time a day or 2 before bagging it.

[EricH]

Originally Posted by sand500

Is there any reason why not to use the 5 volt wago connector on the PD board for the radio and connect the camera with the 12V to 5V connector?

Why, yes there is.

[R42]
All electric power utilized by the Robot shall be distributed from the load terminals of the PD Board (not the M6 shanks).
[...]
B. The wireless bridge power feed must be supplied by the 5V converter (model # TBJ12DK025Z) connected to the marked 12 Vdc supply terminals located at the end of the PD Board (i.e. the terminals located between the indicator LEDs, and not the main WAGO connectors along the sides of the PD Board). No other electrical load can be connected to these terminals (please reference any 2012 Robot Power Distribution Diagram posted on the Kit of Parts site for wireless bridge wiring information.

[nitneylion452]

I also remember that the converter is regulated, while the 5v supply on the PD is not. The radio needs to always have 5v and the PD's supply can't properly accomplish that. Is that correct?

[slijin]

Originally Posted by nitneylion452

I also remember that the converter is regulated, while the 5v supply on the PD is not. The radio needs to always have 5v and the PD's supply can't properly accomplish that. Is that correct?

That is exactly the reason. The dedicated 12V and 24V power supplies exist to ensure that when battery voltage dips below the operational threshold, you maintain communications so there's absolutely no chance of your robot going berko as comms cut out from a lack of power.

[Captaindan]

hot glue the ethernet connections

[de_]

Its my understanding the correct answer is the 12v port on the PDB is highly regulated (ie if the battery voltage droops way down under super high instanteous load (8v, 6v perhaps lower) the output of the port will still be 12v). The finned 12v to 5v converter module is not so regulated (ie the 5v might collapse if the 12v it sees droops below say 10v. But that will not happen its source is the 12v port on the PDB that it is so highly regulated. Clearly FIRST wants the bridge to have 5v at all costs to reduce loss of connection glitchs.

We know this to be true because last year we accidently wired the finned converter to a standard 12v circuit breaker source and gots of loss of connection errors as the battery voltage faded. Clearly the finned regulator regulation had limits.

I have no idea what the regulation specs on the 5v port on the PDB is. You would think it would need excellent voltage regulation for the camera.

[Al Skierkiewicz]

The 5 volt, 12 volt and 24 volt outputs on the PD will be maintained as long as the battery input remains at 4.5 volts or above. The 12 volt to 5 volt regulator requires a minimum of 7 volts input to make 5 volts output. By connecting the 5 volt convertor to the PD 12 wireless output, you will maintain communications. If you connect the convertor to a battery output on the PD ( and your inspector fails to see it), the battery voltage regularly will fall below the required input voltage for the convertor and your radio will reboot.