Transmitting data to the cRIO from the Driver's station via TCP/UDP

[Philipose]

Hi I keep getting an error
"Error 56 occurred at UDP Read in Receiver.vi->Dashboard Main.vi"

The errors are coming from this subVI that you have provided. Do you know if the ports have changed in the new 2012 LabVIEW or if there is another incompatibility?

Thank You for your help in advance

[plnyyanks]

Error 56 means that your code has timed out (i.e. the network hasn't given LabVIEW a response in an appropriate amount of time). Since the error is coming from the Read VI, that means that your code is waiting for a packet to be sent, but one isn't being sent. That makes your code time out.

Since that example wasn't really intended to be used on a robot, I did not specify a Timeout value (see the UDP Read Docs), as the example was really only to demonstrate syntax. Now, that doesn't mean you can't use it on your robot, you'll just have to tweak a few things to get it to run in real time.

First, where in the code structure are you putting this VI (since you said the error happened in Read.vi, I'm assuming this is in the robot part of the code)? It should probably go in Timed Tasks.vi. There, you can make a while loop only for your UDP communication and put a relatively slow delay on it (~100 ms?). Then, you should put timeout values on your network VIs. The value is in milliseconds, so a value around 100 is probably good (this depends on how fast your loop runs).

If this code is on the driver station, then I'd just recommend using the dashboard communication that is already taking place to send data from robot->DS; it'l be much easier to work with (see my last post). But, if you're sending data from dashboard->robot, then this is one of the better options.

If you keep getting errors, you can always unbundle the error out cluster and check if it's a timeout error (the code part of the cluster is 56) and clear that specific error. I can elaborate on that more, if you need.