Motors and SoundTroubleshooting Tips

© 2005 4H-CCS

Problem 1Why can’t I download my program to the RCX?

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Solution 1The RCX was facing the wrong direction. (Don’t forget to turn it on too!)

InfraRed receiver must face IR Tower

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Problem 2Why won’t the motor work?

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Solution 2It was connected to a sensor port. Motor ports are A, B, and C.

Sensor ports

Motor ports

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Problem 3What is wrong with this program?

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Solution 3Bad wiring. Always check for bad wires.

Bad wireMissing wire

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Problem 4This program is supposed to turn on Motor A for 4 seconds, then turn off the motor. What’s wrong?

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Solution 4

There was no “Stop Motor” icon.

Wiring Tips andTroubleshooting

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Many of the problems associated with

programming in Robolab have to do

with mistakes in wiring the Icons or Modifiers.

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Problem 5

This Program looks good at first glance, but notice the broken black arrow on the upper left hand corner of the screen. If you click on the arrow, you will see the list of errors

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Solution 5

The List of Errors shows that neither the input nor the output of the ‘Wait For 4 Seconds’ Icon are wired. It looks like the programmer just laid the icon over the wire. If you grab the icon and drag it down, you can see this clearly.

© 2005 4H-CCS

© 2005 4H-CCS

Problem 6

This Program looks just like the previous one, and again notice the broken black arrow on the upper left hand corner of the screen. If you click on the arrow, you will see a different list of errors.

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Solution 6

This time, there’s only one error listed. It says that the end of the ‘Stop All Outputs’ Icon isn’t wired. If you’re in the ‘Select’ mode of the tools palette (that’s the arrow) and highlight the wire connected to the Red Light, you’ll see a ghost image of the wire connected from the input of the Stop Sign to the input of the red light.

© 2005 4H-CCS

© 2005 4H-CCS

Problem 7

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The List of Errors tells us that the ‘Motor C Forward’ Icon isn’t wired. But whenwe click on one of the errors, neither corner of the ‘Motor C Forward’ Icon flash.And, when we look at the icon, we can see that it is correctly wired……hmm!

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Solution 7

What happened here is that our programmer took the icon off the palette by mistake and rather than delete it, he tried to put it back on the palette. In trying this, all he did was hide the icon under the palette. Delete this icon and the arrow will turn white.

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Problem 8

4

The robot is supposed to go forward for 4 second but it stops after only 1. What could be wrong?

© 2005 4H-CCS

4

Problem 8

Someone forgot to wire the modifier to the ‘Wait for Time’ Icon. Every icon that can have a modifier has a “Default Value.” The default value for the ‘Wait for Time’ icon is 1 second.

Modifiers, Loops and JumpsTroubleshooting Tips

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Problem 9Write a program that plays a beep three times in a row.

This plays sound #3, NOT 3 sounds.

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Solution(s) 9Use 3 Play Sound icons, or use a loop that loops 3 times.

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Problem 10Turn on motor A at power level 1.

This is a numeric constant modifier NOT a power level modifier. (Strangely enough, it doesnot show a bad wire. Hmmmm…..)

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Solution 10Use a Power Level 1 modifier.

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Problem 11Write a program that beeps forever. What’s wrong?

This is a yellow jumpBut this is a red land

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Solution 11Make sure jump and land pairs are the same color.

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Problem 12Write a program that beeps forever. What’s wrong now?

Start Jump to green land

Land here End

Oops!

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Solution 12Be careful not to mix up the order of your jumps and lands!

Sensor Wait-for’sTroubleshooting Tips

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Problem 13Why won’t the light sensor work?

This is amotor port.

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Solution 13Sensors need to be connected to sensor ports 1, 2 or 3.

Sensor ports

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Problem 14What’s wrong with this set up?

The touch sensor is connected to port 1.

But the software says thetouch sensor is on port 3.

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Solution 14Connect the touch sensor to port 3. Or, change the port number in the software.

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Problem 15Why won’t the touch sensor work?

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Solution 15Make sure the cable is connected to the front of the touch sensor.

WRONG RIGHT

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Problem 16What isn’t too great about the way the light sensor is mounted?

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Solution 16If the light sensor is too high, it has a harder time distinguishing between dark and light. Mounting it lower to the ground will help.

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Problem 17What’s wrong with this program?

What is the default port? What is the default port?

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Solution 17Remember: Different sensors MUST be on different ports in the software. If a port is not specified, it assumes Port 1.

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Problem 18This program should turn on motor A until the rotational sensor has turned 2 revolutions, then turn off the motor. Why doesn’t it work?

Hint: What is the default number of ticksin a Wait-for Rotation icon?

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Solution 18The default number of ticks is 16, or 1 revolution. For 2 revolutions, you must specify the number of ticks with a numeric constant modifier.

32 ticks = 2 revolutions

Conditional StatementsTroubleshooting Tips

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Problem 19What’s wrong with this program?

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Solution 19Remember: All forks need a fork merge.

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Problem 20This program is supposed to turn on motor A if the touch sensor is pressed, otherwise turn on motor C. What’s wrong?

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Solution 20The branches of the fork are mixed up. This is a common mistake.

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Problem 21In this program, if the light sensor reads a value above 80, it should turn on motor B. Otherwise, it should beep. Why doesn’t it work?

Hint: What is the defaultlight level value?

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Solution 21The default light level value is 55. To specify a different value, you must use a numeric constant modifier.

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Problem 22What’s missing from this program?

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Solution 22Before every rotational sensor fork, you must reset the rotational sensor.

Rotational sensor reset

Multiple Tasks & TimersTroubleshooting Tips

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Problem 23What’s wrong with this program?

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Solution 23Remember: Only forks need a fork merge. Task splits need red stop lights at the end of each task.

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Problem 24What’s wrong with this program?

Hint: What do all

forks need?

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Solution 24Unfortunately, if you use a task split after a fork, there is NO WAY to merge the fork back together, so just don’t do it.

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Problem 25This program should beep for exactly 5 seconds, but it beeps forever! What’s wrong?

Hint: What do you do immediately after you land on the Red Land?

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Solution 25The problem is, the timer was being reset back to 0 every time you landed. In this program, the timer is reset only once at the beginning of the program.

ContainersTroubleshooting Tips

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Problem 26This program wants to use the value of the red container, which is 22, in the light sensor fork. What’s wrong?

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Solution 26The number 22 was stored in the red container, but the light sensor fork was using the value of the yellow container.

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Problem 27Why is there a bad wire in this program?

bad wire

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Solution 27Remember, forks and loops need to use the value of the container (modifier with white background).

container value

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Problem 28Why is there a bad wire in this program?

bad wire

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Solution 28To store a sensor value in a container, you must use the sensor port’s value.

sensor portvalue