PROS Vision Sensor

VEX V5 Technical Support UNOFFICIAL Tech Support
#1

I am currently trying to use the V5 Vision sensor in PROS C++. I used the V5 Vision Utility on a windows computer to set the first signature to something I wanted to track, and then I tried running the following code:


#include "main.h"
#define VISION_PORT 1
#define EXAMPLE_SIG 1

void opcontrol() {
  pros::Vision vision_sensor (VISION_PORT);
  while (true) {
    pros::vision_object_s_t rtn = vision_sensor.get_by_sig(0,1);
    // Gets the largest object
    std::cout << "sig: " << rtn.signature;
    pros::delay(2);
  }
}

I assumed that 1 in the method call for get_by_sig corresponded to the first signature.
When running the code, however, the only thing that I get in the terminal is sig: 255. This happens if the object corresponding to the signature is visible or not. Is there anything that I am missing?
Thanks.

#2

255 is the value of the signature ID when there was an error. You can check


errno

to see a more descriptive reason.


#include "main.h"
#define VISION_PORT 1
#define EXAMPLE_SIG 1

void opcontrol() {
  pros::Vision vision_sensor (VISION_PORT);
  while (true) {
    pros::vision_object_s_t rtn = vision_sensor.get_by_sig(0,1);
    // Gets the largest object
    std::cout << "sig: " << rtn.signature;
    if (rtn.signature == 255) std::cout << " " << errno;
    pros::delay(2);
  }
}

I suspect you’ll see 33, corresponding to EDOM which indicates that the vision sensor wasn’t able to find an object with that size/signature combo. You could also see 22 for EINVAL or 117 for EHOSTDOWN (which means we couldn’t communicate with the Vision Sensor for some reason).

#3

Thanks for letting me know! I did some more troubleshooting and figured out that the problem was with the vision sensor utility not properly saving signatures.

#4