Hello, I am currently working on a project with an analog sensor and a stepper motor. I want the sensor to collect data when the motor turns to angles of specific increments. Currently I have labview tell the arduino what angle increment the stepper should move in through the serial monitor. (Ex. I send "5", and the motor will move to 5, 10, 15, 20... degrees). When it reaches that angle, I have the arduino print on the serial monitor what angle it is currently at which Labview should read. I also have arduino write "M" on the serial monitor if the motor is still moving so that labview knows to not take any data from the sensor. I currently don't have the sensor on me so I have a random number generator instead. Labview is able to communicate with the arduino and tell it what increment the stepper motor should move in. However it doesn't seem to be reading what the arduino writes back at all. I'm sure this is a trivial problem but I am still having a hard time with this even after reading the other threads. Any help would be graciously appreciated! #include <Stepper.h> const int stepsPerRevolution = 2048; // change this to fit the number of steps per revolution const int rolePerMinute = 15; // Adjustable range of 28BYJ-48 stepper is 0~17 rpm const int degree = 100 * 30; // will be geared down int increment = 0; // initialize the stepper library on pins 8 through 11: Stepper myStepper(stepsPerRevolution, 8, 10, 9, 11); void setup() { myStepper.setSpeed(rolePerMinute); e the serial port: Serial.begin(9600); } void loop() { while (increment == 0){ if (Serial.available() > 0) { int receivedInt = Serial.parseInt(); // read the incoming byte: Serial.print(" Increment Set To:"); Serial.println(receivedInt); increment = receivedInt; } } Serial.println("S"); int i = 0; int end_angle = 180 + 1; while (i < end_angle){ myStepper.step(100 * 180); int angle = i * increment; //Serial.println("Degree: "); Serial.println(angle); delay(1000); i ++; Serial.println("M"); } Serial.println("END"); }

I don't really know how I solved it but everything works now!- I moved the code in the void loop to setup- I changed the byte to 100 The code definetly could be cleaner but if it works it works. #include <Stepper.h> const int STEP_PIN = 8; const int DIR_PIN = 7; const int START_PIN = 2; //step increment: 1 step = 0.01 degree. Therefore 1 deg = 100 step //const int stepsPerRevolution = 200; const int stepsPerRevolution = 2048; // change this to fit the number of steps per revolution const int rolePerMinute = 15; // Adjustable range of 28BYJ-48 stepper is 0~17 rpm const int degree = 100 * 180; const int TURN_PIN = 3; String a; int increment = 0; int end_angle = 180 + 1; // initialize the stepper library on pins 8 through 11: Stepper myStepper(stepsPerRevolution, 8, 10, 9, 11); void setup() { myStepper.setSpeed(rolePerMinute); pinMode(START_PIN, INPUT); pinMode(TURN_PIN, OUTPUT); /* pinMode(STEP_PIN, OUTPUT); pinMode(DIR_PIN, OUTPUT); */ // initialize the serial port: Serial.begin(9600); int RESET = 0; while (increment == 0){ if (Serial.available() > 0) { int receivedInt = Serial.parseInt(); // read the incoming byte: Serial.print("Increment Set To: "); Serial.println(receivedInt); increment = receivedInt; Serial.print("Degree: "); Serial.println(0); delay(100); } } int i = 1; while ((i * increment) < end_angle){ //myStepper.step(100 * 180); myStepper.step(increment * 180); int angle = i * increment; Serial.print("Degree: "); Serial.println(angle); delay(100); i ++; } Serial.println("END"); RESET = 1; delay(1000); Serial.println("RESET STARTED"); myStepper.step(18 * 18 * -1); delay(100); Serial.println("RESET ENDED"); } void loop() { }

DO NOT USE THE BYTES AT PORT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (still not enough emphasis) You are dealing with an ASCII protocol, so let the VISA Read do all of the hard work for you. Just tell the VISA Read to read more bytes than you ever expect in a message and it will read the entire line for you. After that, it is a matter of you making a proper message on the Arduino side and properly parsing it on the LabVIEW side. I would recommend taking all of your data from a single loop in the Arduino and formatting that into a single line, maybe using a comma as a delimiter.

LabVIEW

VISA Serial + Arduino Read Buffer not working (Write works)

Solved!

@rolfk wrote:

@Gyc wrote:

Thank you all for the explanations.

Today is already late, I'll post one of the latest vi's where I found this error tomorrow.

I am aware of the response delay between sending a command and receiving a reply, so I do take into account that bytes may not be immediately available - quick&dirty trick is just inserting a delay between send and receive and tweak it.

It is a bit of a Heisenbug, yes - but we learn to recognize and deal with these early in our "careers" 😉 😁

And if you are a little further in your career, you might learn that instead of creating Heisenbugs, there are more reliable ways of doing things. Ways that work in production, day in day out, without introducing long delays that slow down your communication unnecessarily in 99.9% of the cases, just to try to avoid that Heisenbug. Except you don't avoid it really, even very extreme delays may sometimes not be enough. You never will know, except that your system spuriously causes errors.

Your serial port or network protocol (really any protocol that is based on a byte stream) should either be in ASCII and include a well defined EndOfMessage character, or if it is binary it should use fixed size messages or messages with a fixed size header that lets you determine how much data the remainder contains. Anything else is a hobby project, not a real device.

Delays only for assessing and studying the issue.

Delays are never a good bet for a stable and reliable solution - nature always finds a way to blow it up 😎

Message 11 of 11

(64 Views)

LabVIEW

VISA Serial + Arduino Read Buffer not working (Write works)

Re: VISA Serial + Arduino Read Buffer not working (Write works)