Need help communicating with the D-Link DAP1522

[Amit Galor]

Hello, I'm having trouble getting communication wirelessly with the robot-
We use an Edimax BR-6204Wg router as the "bridge" connected to the computer and the D-Link DAP 1522 as the access point, and we used the "how to configure your radio" pdf to set the settings of the routers, but we don't get communication. We believe that the problem is with the D-Link's settings, because when we used last year's access point (Edimax EW-7206APg) we did get robot communication. We also got communication when using the classmate's wifi- the only problem is the communication between the Edimax router and the D-Link access point.
A super weird thing- when the robot is connected to the D-Link and everything, and we connect to the Edimax wireless network with an IPOD (for some reason my teammate tried it) then we suddenly see Robot communication in the driver station- but bringing an ipod to the competition isn't the solution ><".
Anyway, if you have a clue of what the problem might be I'd be glad to take advice. Plus- how does the communication work in the competition? a super router from the FMS connected to the classmate with an ethernet cable?

[Ryan Foley]

Amit,

The new D-Link DAP-1522 unit functions both as a bridge and an access point.

When not at competitions, you can switch the DAP-1522 to AP mode (using the switch on the back of the unit). This will turn the unit into an access point, allowing you to connect directly to the robot using the driver station's wireless connection. You shouldn't need the Edimax unit at all.

At competitions, the DAP-1522 should be used in bridge mode. The "bridge" mode allows the DAP-1522 to connect to the field access point when competing in a match. The driver station is connected to this same access point via a router and Ethernet cable. Communications from the driver station pass through the router, access point, and DAP-1522 before reaching the cRio on the robot.

Hope this helps.

[Amit Galor]

Hello Ryan,

Just to make thing clear, at the competition an access point AND the DAP-1522 will be on our robot (while my driver station is connected to the FMS's router)?
(To my understanding: DS=>Field router=>a different access point=>DAP-1522=>cRio. Did I misunderstand something?)

About non-competition usage: We did manage to get communication with the DAP-1522 using the classmate, but in order to test software with a different computer (debugging a deployed software) we used the Edimax router. The only reason we used the Edimax access point is because the DAP-1522 didn't work.

I'll be glad to finally be sure about of everything works, so I could also help other people when they're having trouble.

Thanks,
Amit.

[Ryan Foley]

Originally Posted by Amit Galor

Just to make thing clear, at the competition an access point AND the DAP-1522 will be on our robot (while my driver station is connected to the FMS's router)?
(To my understanding: DS=>Field router=>a different access point=>DAP-1522=>cRio. Did I misunderstand something?)

No, the FMS router and access point are on the side of the field near the scoring table; the D-Link unit is on the robot. The field router and access point connect all 6 driver stations to the corresponding robots. The "bridge" mode allows the D-Link to connect to the field access point.

Hope this clears things up.

[Ryan Foley]

An updated guide to configuring the D-Link DAP-1522 radio has been posted on the Kit of Parts website.

Direct Link: http://www.usfirst.org/uploadedFiles...adio_Rev_A.pdf

[BoomerGeek]

You guys do a wonderful job and I very much appreciate it.
I do have a suggestion I hope you will consider.

How can every team determine if their signal is marginal versus very strong on the actual FMS competition field?

Does the the FMS router and access point on the side of the field near the scoring table detect and monitor the WiFi signal strength and number of packet errors from each robot during the entire time of each match?

Would this be something that could be easily collected and reported so a team can try to eliminate WiFi as a potential source of some of their problems?

It would be nice if there was a more robust test of the team's D-link once it is placed on the robot- I think Team 241 was plagued by problems this past weekend's competition at GSR because of poor D-link placement on our robot.
We did report we were having trouble communicating with our robot in several matches: in one match, it did not move at all. It was only after the competition was over that we started to consider that some of our trouble could be related to the placement of our D-link.

The "How to Configure Your Radio" could be improved if it gave guidelines about D-Link placement on a Robot and gave expected signal strength and error rate.

I also wondering if D-Link placement should be a robot inspection issue, as intermittently losing radio connection to a robot makes a robot less controllable and therefore less safe. (I.e., There is already a rule: "<R53> The DAP-1522 radio must be mounted on the ROBOT such that the diagnostic lights are visible to FIELD personnel.
Teams are encouraged to mount the radio away from noise generating components such as the CIM motors. By making the diagnostic lights visible, FIELD personnel are in a better position to assist teams." in the competition manual,. It could possibly be enhanced to "The D-Link shall not be placed in the close proximity (less than 6"(?) away) of motors and motor controls nor deeply packed within a metal frame of a robot. A strong recommendation of at least 10"(?) high on the robot and mostly not blocked on the sides or top by metal nor other radio signal blocking material. The power and Ethernet connections to the D-link shall be snug and not lose contact if wiggled.


Is there any data on how many robots have poor radio performance due to bad placement of the D-link? (I'm guessing it could be very significant.)
(People have a natural tendency to place electronics deep in the robot to be well protected).

Thanks again.

[jsteele]

We have some issues with losing DAP1522 communication as well. We've noticed that it will suddenly lose connection if the robot is bounced or moves rapidly, however it doesn't appear the power connector is coming loose (I don't recall seeing the D-Link lights go off). The DC connection into the router doesn't look too solid however. I remember seeing a suggestion somewhere to put a small bead of hot-glue to keep it attached, but IMO it's the connection inside that is bad.

But, as I just mentioned, I don't remember seeing the D-Link lights go off, so i'm wondering if the circuitry inside the D-Link is not capable of handling the hard hits a robot in competition will encounter.

In the end, the majority of our testing with the D-Link WiFi failed because of intermittent connectivity.