How to calculate conveyor speed?
The actual speed is irrelevant... As long as the code can keep up... The encoder will tie directly into Timer1 and with a prescale we can have up to 20Mhz + ... The counter will be serviced by the CCP module every falling edge... All I need to know is quantities of each product...
Product length in a diagram = 190 mm and and there are five product between detection point to a rejection point
There is VFD to control the speed of the motor so we can also test the program at low speed speed of conveyor. There is one button to increase/ decrease speed of conveyor
sorry I didn't understand We are able to reject one object but how we will reject more than one object on the conveyor
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dim unsigned long queue[6];
volatile byte putIndex = 0;
volatile byte getIndex = 0;
volatile boolean emptyQueue = true;
// add an item to be rejected to the queue
void putQueue() {
const unsigned long positionDelay = 16500;
queue[putIndex] = getCounter + positionDelay;
putIndex=++putIndex%6;
emptyQueue = false;
}
// get the next item to be rejected from the queue
unsigned long getQueue() {
if(!emptyQueue) {
byte tempIndex;
tempIndex = getIndex
getIndex=++getIndex%6;
emptyQueue = (putIndex==getIndex);
return queue[tempIndex]
}
else {
return 0
}
}
// obtain the current counter value
unsigned long getCounter() {
/* insert code to get the current counter value and return it as the function value. No parameters are necessary. */
}
// scan or test the object to determine if it should be rejected
boolean testObject) {
/* insert code to test the objects and return false if it is a reject */
}
// physically reject a failed item
void reject() {
/* code to physically reject the object. */
}
// main processing loop
void loop () {
unsigned long Counter;
boolean rejectionDone= true;
const unsigned long deltaCounter= 2;
if (! testObject()) putQueue( );
if (! emptyQueue && rejectionDone) {
Counter = getQueue()); // next failed object
rejectionDone = false;
}
if (! rejectionDone &&
abs(Counter-getCounter()) <= deltaCounter) {
// failed item is at rejection point
reject();
rejectionDone= true;
Counter = 0;
}
}@JohnInTX I understand shift register but I don’t understand how it would help to reject multiple bad object
#include<stdio.h>
int main(void)
{
int a = 1;
printf("\nNumber is Shifted By 1 Bit : %d",a << 1);
printf("\nNumber is Shifted By 2 Bits : %d",a << 2);
printf("\nNumber is Shifted By 3 Bits : %d",a << 3);
printf("\nNumber is Shifted By 4 Bits : %d",a << 4);
printf("\nNumber is Shifted By 5 Bits : %d",a << 5);
printf("\nNumber is Shifted By 6 Bits : %d",a << 6);
printf("\nNumber is Shifted By 7 Bits : %d",a << 7);
printf("\nNumber is Shifted By 8 Bits : %d",a << 8);
return(0);
}@LesJones If I follow John's approach Do I need to use a timer?
No, you don't. The shift register and most of the other approaches described here are based on distance as determined by the encoder. You would use one of the internal timer/counter peripherals in the uC as a counter that counts the pulses from the encoder to determine what distance the belt has traveled from the sensor.
You should look again at the PLC example I posted if you want to understand the concept. You don't have to know PLC (I don't). It's the basic concept that you need to understand. After that, whether you use a shift register, an event list or any of the other distance-based ideas described here, the concept is the same. You are not interested in the numeric value of the contents of the shift register. You are interested in the bits themselves as they get shifted. The bits are like the stickers on the boxes in my example. The PLC example I linked is animated so that you can follow along.
The distance between the sensor and the reject point is 1200 mm.
#include <xc.h>
#define _XTAL_FREQ 20000000L
#pragma config FOSC=HS
#pragma config WDTE=OFF
void main(void)
{
unsigned int ShiftReg = 0; // Init to 0
INTCON =0; // No interrupts
PORTC = 0;
TRISC = 3; // RC0 encoder & RC1sensor inputs
TRISD = 0; // Portd outputs
T1CON = 2;
while(1)
{
while(RC1); // wait while high.
while(!RC1); // wait while low.
// code for shift register here ?
TMR1H = 0xBF; // Load starting value
TMR1L = 0x8C;
TMR1IF = 0; // Clear interrupt flag
TMR1ON = 1; // Start TMR1
while(!TMR1IF); // Wait for timer spill
TMR1ON = 0; // timer off
RD4 = 1; // set output pulse high
__delay_ms(800); // Delay to see ouput ( inbuilt delay)
RD4 = 0; // set output pulse low
}
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