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Phoenix Spud
01-29-2010, 06:39 PM
Hi all,

We are having some trouble with our wireless bridge. Here is the situation:

We have hooked up our cRIO, router, and bridge to the robot and all was great. We had some minor trouble but we figured out it was the cRIO not getting enough power once the motors were going. (our batteries still have not arrived, so we are using 12V 7 AMP batteries. They only last about 15-20 minutes.) We even took our robot to a sponsor yesterday to show them the robot, and we ran wirelessly. They were really impressed. Now, our bridge is getting really slow/flaky on us. We are ping-ing it and about half of the time, we get a "request has timed out" error. We hooked up the bridge to a computer and we can see that it is not seeing all the ping messages. The ping messages that it does respond to are really slow. We have checked the connector and it is OK, we even plugged the bridge back into the wall to make sure that the connector was not the problem.

Any ideas on what we are doing wrong? Is our wireless fried somehow???

Thanks!

Phoenix Spud
01-29-2010, 08:29 PM
We are pretty sure that the bridge is dying and/or flaky. Does anyone know where we might find a replacement in Australia? We are getting pretty desperate after trying 20+ stores online. We have sent some students over to the mall to see if they can find one, but we don't have high hopes.

Al Skierkiewicz
01-29-2010, 10:04 PM
Phoenix,
The wireless bridge must be wired to the specific gray connector on the Power Distribution Panel marked 12 volts. This is not the 12 volt battery but a specialized power supply internal to the PD. It supplies 12 volts even if the main battery should go down to 5 volts. What you describe is typical for the bridge when it is wired to one of the normal power outputs on the sides of the PD.
Also there are two antennas inside the bridge. If you look at the front of the bridge with the power connector and LAN connector facing the floor, one antenna is parallel to the bottom edge of the case on the left side and the second is parallel to the left side of the case in the middle. They are mounted about 1/4" inside the case. Yes, they are at right angles to each other. These two areas should be kept away from large pieces of metal and motors to insure good reception.
The small battery you are using cannot supply enough current to run your motors and provide more than 5 volts to the internal power supplies. When you are running a lot of motors or when you are trying to climb, the voltage will sag. When this happens the bridge, Crio and camera power supplies may shut down. If that occurs, the Crio will need to reboot and the bridge may not find the Crio as it boots. If you need to test with a better battery, motorcycles and personal water craft use this same size and capacity 12 volt battery. If you can get one cheap, I think you will find better performance until your First batteries arrive. Just remember you may only use the First batteries or the same type during competitions.

SteveGarward
01-30-2010, 02:24 AM
Thanks Al for all the ideas.

We were having large, intermittent latency issues even when it was plugged into mains power.

When we changed the wireless channel (to try to avoid any possible interference from other wireless around, since we're on the electronics engineering level of a university, with wifi in the room as well), the latency issues went away. We went from ping requests getting up to 2s or timing out, to 1ms response time, 15ms at most, consistently over a 3 minute period.

So for now we're assuming there was enough happening on the channel it was picking (in auto mode) that it was causing us some issues. Time will tell if this has permanently solved out problem.

Al Skierkiewicz
01-30-2010, 10:19 AM
In my work we call that a "smoking gun". I hate intermittents that have no cause.