VexNet Question

Im tottally new to VexNet; I just put it on our competitional robot today. I updated easyC, put the new VexNet firmware on the micro controller, and the whole nine yards. However, somethings wrong. I put the program in the vexnet comp template, wrote my program in Rx1, then built and downloaded to the vexnet backpack ont he transmitter in the serial input. Both the robot and transmitter were on. When it is done downloading, the robot twitches, so I know there is at least SOME kind of connection between the computer and robot via the transmitter and vexnet. When I go to control the robot, even after 20 seconds, I get no response. Any help would be appreciated. Batteries were all new and charged.

First off, what program are you using to program this in?
If its easyC, do you have the values for Autonomous and Driver Period set to 0 instead of the usual 20 and 254. Master Code version should be v10.

Check the lights on the VEXNet module on the bot - they tell a story, and could probably diagnose the problem.

Do you have the backup battery plugged in? If not sometimes the robot will stop working after a little time.

Backup battery is in. HOwever i dont understand what you mean by the 0 value. I am in easy C. Also, the “Game” light on VexNet ist on or anything. The “Robot” light is red and the “VexNet” light is blinking.

When you have a Competition Template you have to set the values for how long the program runs for. For crystals, it is 20 second autonomous and 254 second driver.

Game light shouldn’t be on unless it’s hooked up to a field or to a competition switch (either virtual or real).

And Spen, that wouldn’t really affect anything since it’s automatically 0 and 0 when you load the template and you can’t change it.

Are any other lights a different color other than green and flashing in any way?

Well as i said “VexNet” is flashing, “Robot” is solid red. Thats all. After i download the progam, is there anything else I have to do?? use this to help you decode the lights. It looks like to me that the robot is linked to the controller but the main battery is dead. Can you post your code?

If the VEXNet is a fast green, then the robot is linked. Good.

If the Robot is solid red, the main battery is near dead. Replace it with a charged battery, and insure that it is properly and fully charged.

For further reference, go to here:

The last page is all the light codes. Use them and that usually helps solve minor problems.

AMENDMENT: The red “Robot” light is blinking slowly. According to the chard, that means the one controller is good, so problem:Still unresolved.

Can you post the code? EasyC takes both parts of the code to work. the .bds and the .ecp file.

The speed of the blink indicates controller connectivity. So a fast blink is 1 controller connect, and solid on is 2 controllers connected.

The colour of the light indicates the battery condition. So a Green light means full battery, an orange half and red is empty.

For Vex robotics, the “empty” Voltage is set to be below 5v which is the supply voltage for the PIC. Anything below this is liable to cause randomness at best, or total failure at worst (as you seem to be suffering from).

Try charging your battery or replacing it with an AA battery pack…

I have also noticed that the VexNET wifi KEY uses a large ammount of extra power, try connecting using the USB cable and see if this allows you to control the robot.

Again, I am a tottal noob. How should i upload the program? A Link?

well, teathering works. The robot light goes solid green. So its not battery…its the keys or something with the wireless…

That means that the code works if it works tethered. When you have the keys in is their a blue light on BOTH keys. Even if there is, jiggle them and see if you can get a better connection with them.

My team is having a similar problem right now & we’re leaving for Nebraska tomorrow!!! The vex nets weren’t pairing up. We think that the robot overheated so give it time to rest.

Call tech support at IFI. They can give you a quick way to discover what your problem is. Good luck.

We’re having the same problem as Mendham Robotics. The Robot light flashes red slowly and the VexNet light flashes a fast green. Both batteries are fully charged, so the red light doesn’t make sense to me.

and I can’t download the code even with the USB cable connected that is used to sync originally

Since you guys can tether, I’m assuming its one of 2 things:

  1. Your competition template is wrong

  2. You did not sync your vexnet

  3. In easy c, right when you open your project, The first thing you should see is the competition template. You should see something like


inside number here should be 0 for both. If it is not 0, you can create a new competition project, and pick vexnet wifi, or you can just change them to 0. If they are 0, then that would probably mean a problem with the vexnet and/or controller. These are the things that you want to make sure.

  1. If the middle LED (I believe it was called vexnet), is not turning green even after you wait, then the vexnet is probably not synced. Look at the end for simple direction on syncing.
  2. If the middle LED is green, but the top LED (I think robot?) is red, AND blinking slowly, that means your controller is off (on the front). Turn it on so you hear the beep of the controller turning on, and you should see the LED blink either fast red, or fast green, which indicates that everything is good.

To sync your vexnet, turn both vexnet modules off, and pull the key(usb stick) out on both. Get the USB Male-to-Male cord that they provide, or your own, and connect the two vexnet modules. Turn ONE of them on, doesn’t matter which one, and you should see the other one turn on as well. You will see both turn yellow/orange blink LEDS, then they should turn green. once they turn green, you can turn off the one you turned on, and pull out the cords. They are synced.

Hopefully this helped out. If the problem is something else (such as all 3 LEDs on one of the vexnet modules just blink red the whole time), then you will need to call tech support.

look at my post, or simply, turn the controller on (on the front). You have to make sure that the front of the controller AND the vexnet module are turned on. However, the vexnet module controllers the actual ON OFF, of the controller, so if the vexnet module is off, even if the front of controller is set to the on position, it will stay off. I have my drivers tape over the front switch of the controller so that they do not accidently turn it off, and forget to turn on before a match. We have crapped out of couple of matches because of this problem -.-