DLink / D-Link resets going over bumps! Thoughts?

Our programming team has been using the DLink (D-Link) DAP-1522. Life is great if robot is on blocks or on a test board. However, while running over carpet, it will set a bump in the carpet and viola - communications are lost and the unit can be seen rebooting itself.

Question 1: Anyone having issues with either the power momentarily being lost on their DLink or accidentally being reset?

More Info:
-DLink is securely on the robot
-all electrical connections from PDB (pwr board) to converter to barrel-plug and into DLink all look fine and are secure

-We do have additional DLink and will try those as well and see if the issue continues.
-If it continues, we may crack-open the DLink and possibly solder the power connector to the board - bypassing the code-barrel-plug/power-jack.

Question 2: Thoughts? anything else to try.

is power to the cRio being lost? or are you sure it’s only the bridge?

Good question. My focus has been on the DLink itself. I suspect not.

The reason for my comment is that I ran after the robot and was constantly watching the DLink. The LAN connection that the cRIO is plugged into will flicker wildly while communications are going on. When the DLink ‘resets’, all the LED’s seem to turn off and then on. About a minute later, the DLink port for the cRIO flickers wildly again and we are off to the races.

When the reset occurs, the four LED’s for the four ports blink off then on (or vice versa). If the cRIO was losing commuications with the DLink or losing power, the other LED’s on the DLink shouldn’t turn on and then off.

My team has a similar problem. We would randomly lose robot communication for the driver station, but I at the time did not think much of it. I need to inspect it further on Monday.

Realize that the radio was designed to sit on an office shelf and not to get bounced around.

I would focus my attention on the power connector at the radio. This was a known problem with the previous device. Put a service loop with strain relief on the power cable and let us know how it works.

Here is a slide I made last year for training my robot inspectors…





In regards to the power cord (barrel plug), it’s connected in such a way that the barrel plug end doesn’t have any tension on it. No strain on the power cord.

I suppose what we could do is rig it such that the plug has no way of moving in the DLink power jack connector.

I know I’m ‘reaching’ but any thought that whatever mechanisim is used to reset the unit (you know, that little pin hole) might be connecting and causing the unit to reset?

Two thoughts on my part have been to (a) solder the power cable directly to the motherboard of the DLink and (b) ensuring that there is nothing in the area of the reset button mechanism that could be causing a momentary closing of a circuit.

As I said, this was an ongoing issue with the old radio. I would see this four or five times in any given competition and the illustrated strain relief has never failed.

Just like PWM wires in victors, it is smart to hot glue ANY connection on the robot that does not have a positive locking feature that prevents it from coming loose.

It doesn’t take much, it’s easy to peel off, but it will keep you safe. It’s smart to glue the reset button too on the older one since it had enough mass to trigger going over the bump.

We would shake our heads every time we saw a robot go to the fast-flashing (no connection) light during breakaway. 9 times out of 10, it was unsecured connections. Why beat yourself? It’s hard enough to do well as it is.

Tom, Mike, all,
Thanks for the suggestions. Hot glue it is. I’ll have our electrical team review the diagram in the earlier post and the ‘hot glue’ ideas. I’m putting the glue gun in my backpack now to make sure we have one tomorrow night.

We’re not in panic mode on this yet. Just don’t want to head that way.

Again, thanks for the suggestions.
-Ted

Ted,

After a few days, post an update if this worked. I’d be interested to know if this is an issue with the new radios…

Regards,

Mike

While on the subject of the DLINK radio…

<R38> B. The radio power feed must be connected via the 5V converter (model # TBJ12DK025Z) 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 see the 2011 Robot Power Distribution Diagram posted online at www.usfirst.org/frc/kitofparts for wiring information).

I just discovered rule this yesterday afternoon while looking for something else. Ay-yi-yi! We’ve been running ours directly off the 12Vdc terminals. It still works but I hope we haven’t somehow damaged it. Maybe everybody else but us knew this but you might want to check your robot to be sure that the converter is being used to provide the correct voltage to the radio.

I doubt if it was damaged. I think the main reason for powering from the dedicated terminals is to provide a kind of UPS function. The battery voltage can crash to very low levels when you put large demands on it (like four cim motors at near stall…).

FIRST is trying to make the communications as robust as possible.

Change the wiring to their recommendations and move on…

As long as you used the 12v-to-5v converter it’ll survive.

The real problem with using the red/black wago connections for the radio is that a significant drop in battery voltage, e.g., full-power robot pushing contest, will risk resetting your radio.
The special 12v connector (and the 24v cRIO power) are protected against voltage drops to avoid resetting either one of those devices during a competition match.

This probably isn’t your problem, but just for the record we had hellish problems last year losing connection. This persisted through two regionals. Our drivers spent more time with their hands in their pockets than on the controls.

After getting back and experiencing the same problems on a completely different robot we investigated further.

We found vigorously shaking the radio had NO effect, but gripping it lightly on the top and bottom killed it instantly! We took it apart and looked at it under a magnifying glass for aluminum shards, cracked traces, anything. Finding nothing we put it back together and it worked just fine. Go figure.

That’s why I’m a mechanical guy.

I just got through purchasing another DLink because our team wired it directly and fried it. $107.00 from Office Depot because we didn’t RTM! Please learn from our eagerness to get the robot rollin’!

If you are loosing something when you run over bumps check these things…

  1. lightly tap the red button on the main breaker. Do lights on the robot flicker? Replace main breaker it is defective.
  2. Does your cRIO move around? It may be shorting to the frame of the robot when it moves. Some RS770 motors are being delivered with a short to case. If you are using these motors check continuity from each motor terminal to motor case. You may be sending power hits to the Crio.
  3. Triple check the power wiring coming from the radio connector on the PD. These are notorious for being improperly terminated. The wires should not pull out when tugged and there should be no visible whiskers that can short the two wires together.
  4. Check that the battery terminals on the PD are snug and have a lockwasher under the nut that hold the terminals in place.
  5. Check the battery connections by moving all #6 wire with the robot turned on. Flickering indicators are a sign that something is loose.

Any body ever heard of a converter that is bad? On our converter, when we power 12v in we get 7.3v out. That doesn’t necessarily concern me, what does concern me is that when we plug in the power to the D-Link we get nothing; we tested voltage, and we exactly get 7.3v out of the plug (as expected - the plug that came with the D-Link gives 5.2v in the same orientation) yet the D-Link is only pulling 2mA from the converter. Something seems bad here…

We do know:

  1. If we bypass the converter, everything “works” (we accidentally did that before adding in the converter). This tells me the extra plug we bought (same size as the one that came with it) fits and works.

  2. If we plug in the power cable that CAME with the D-Link, everything works fine (even after the fact).

  3. With the converter in-between, voltages look fine but we’re pulling almost no current.

Does this sound fair to say the converter is possibly bad?

-Danny

That does sound suspect, I remember when we wired ours up I probed it with the multimeter before connecting the radio to confirm polarity and it was reading around the expected 5V under no load. Some SMPS don’t work well without load, but if you’re connecting it to the router and not getting anywhere, that’s weird.

Are you sure your router is good? It seems strange it wouldn’t try to pull more current. If the problem was in the converter not delivering more current the voltage should take a dive.

Matt

What about that button on the side of the D-link? (I believe it has circling arrows) Is it getting pressed when the robot hits a bump in the carpet? Could that be resetting the D-link in some way?