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

[tdressel]

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.

[MrForbes]

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

[tdressel]

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.

[MagiChau]

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.

[Mike Betts]

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.

[Mike Betts]

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

[tdressel]

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.

[Mike Betts]

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.

[Tom Line]

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.

[tdressel]

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

[Mike Betts]

Originally Posted by tdressel

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

[BitTwiddler]

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.

[Mike Betts]

Originally Posted by BitTwiddler

... 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...

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...

[Mark McLeod]

Originally Posted by BitTwiddler

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.

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.

[JCharlton]

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.