Troubleshooting DIY DRO Problems

No LEDs Light Up or Blink on The Controller

Symptom

After being powered TouchDRO controller doesn't show any signs of life

Cuase

This problem is most often caused by the use of incorrect power supply.

Solution

  1. Unplug the controller immediately to avoid permanent damage
  2. Ensure that the power supply provides DC voltage, not AC
  3. Ensure that the power supply uses correct polarity
  4. Using a voltmeter, verify that the power supply provides voltage in the correct range. Refer to your controller's details page for more information
  5. Try using a different power supply and/or different outlet

Heartbeat LED is not Blinking

Symptom

Power LED (if present) and BlueTooth LEDs are on but the the heartbeat LED is not blinking. TouchDRO application fails to connect to the controller.

Cause

This is a result of the main Microcontroller (MCU) not working properly. It could be either due to low power supply, the MCU not being programmed correctly, damaged MCU or a defective board.

Solution

  1. Using a voltmeter, verify that the power supply provides voltage in the correct range. Refer to your controller's details page for more information
  2. Visually inspect the board to see if there any shorts or damage to the PCB
  3. If using a self-built controller, verify that the circuit is built correct, or try reprogramming the MCU
  4. Ensure that the MCU is inserted correctly (if using the DIY Mixed Scale Kit)

Position Doesn't Change When Scales Move

Symptom

The board is operational, connect to the application but when a scale is moved the readout ie either 0 or doesn't change from some random value.

Causes

This problem is caused by the controller not being able to read the position from the scale, either because the scale is using an unsupported protocol, or the connection between the scale and the controller is incorrect or broken.

Solution

  1. Verify that the scale is supported by the controller/firmware you are using. Refer to the Selecting DRO Controller  page for more info on supported scales.
  2. Restart the controller with the scale plugged in. Protocol detection happens during the first two seconds after the board is powered and if the scale is not plugged in during the detection routine the firmware might use the wrong protocol.
  3. Ensure that the scale is wired correctly and securely. Refer to the Hardware Setup  page for connection instructions.

Scale Has a Dead Spot

Symptom

The scale works correctly across most of the travel, except one spot where the readout freezes.

Causes

There are two potential causes of this problem: either the scale is defective and can't read the encoder strip in certain spot(s), or there is intermittent connection problem that manifest itself when the cable is in certain position.

Solution

  1. Ensure that all connectors are inserted securely and don't become loose when the scale is moved into the dead spot
  2. Move the scale to the dead spot and wiggle the connectors - if the problem goes away, the connector is loose.
  3. Try using a different cable and see if the problem persists - if the problem goes away, replace the cable.
  4. Try plugging the scale into a different axis input - if the problem goes away, the connector on the board is damaged and needs to be replaced.

Position Increments/Decrements Regardless of Direction of Travel

Symptom

Regardless of the direction of the movement of a quadrature scale, the position alway increments (or decrements).

Causes

This problem is caused by either A or B lines of a quadrature controller not being connected properly (missing connection).

Note: if a capacitive scale exhibits this problem, the scale is most likely defective and needs to be replaced.

Solution

  1. Unplug the controller board from the power source
  2. Check that the scale is connected correctly to the controller
  3. Check the continuity between the pins on the board and connection points in the reading head (if accessible), or at least the back side of the scale connector.

Position Resets To 0 Randomly

Symptom

At random places position is reset to 0 on one axis, but the controller stays connected to the TouchDRO application.

Causes

Most common cause of this problem is a ground loop that causes excessive interference on the power supply lines. In some cases this interference is strong enough to cause momentary reversal of power supply polarity, this resetting the scale. It could also be a loose ground or Vcc connection.

Solution

  1. Ensure that power supply lines are wired correctly and securely.
  2. Eliminate ground loops in the setup. For more information refer to the Avoiding Common DRO Scale Problems  page

Readout Jumps and Stays at a Wrong Position

Symptom

At random times the scale jumps to a different position and doesn't jump back.

Cause

The cause is similar to the one above.

Solution

  1. Ensure that power supply lines are wired correctly and securely.
  2. Eliminate ground loops in the setup. For more information refer to the Avoiding Common DRO Scale Problems  page

All Scales Reset to 0 Randomly

Symptom

All connected axes reset to 0 at random times; TouchDRO might or might not lose connection to the controller.

Cause

The most common cause of this problem is loose or unreliable power supply connection. In some rare cases it could also be a severe interference caused by a ground loop, similar to the problem above.

Solution

  1. Ensure that the power supply is connected securely and uses the correct connector. TouchDRO boards and kits use standard 5.5mm O.D, 2.1mm I.D. connectors with the barrel connected to the ground.
  2. Ensure that the power supply is plugged in securely into the wall socket.
  3. Ensure that the power supply provides correct voltage. Refer to your controller's details page for more information.

Readout Jumps Back and Forth

Symptom

Scale readout momentarily jumps to a random position and quickly returns to the correct position.

Cause

This issue occurs due to noise in the Clock or Data lines that is mis-read as scale reading. There are two common causes of this problem. It could be either an unreliable connection on Clock or Data lines, or a result of interference due to a ground loop or improperly shielded cable.

Solution

  1. Ensure that the Clock and Data lines are connected securely to the controller.
  2. Eliminate ground loops in the setup. For more information refer to the Avoiding Common DRO Scale Problems  page
  3. Consider shielding the cable using metal shroud, grounded on one end, or using better quality shielded cables.

Readout Jumps to a Wrong Position In One Spot

Symptom

The scale readout jumps by a large number but returns to the correct readout when moved back.

Cause

This issue occurs for one of the two reasons. In some rare cases scale position encoder strip is defective, causing the scale to read wrong position. More commonly it is a result of some Chinese manufacturers deviate from the standard protocol when it comes to representing negative numbers, which causes TouchDRO to mis-read negative numbers

Solution

  1. Verify that the scale work with it's original reading head correctly.
  2. Ensure that the scale is supported by TouchDRO controller/firmware. Refer to the Selecting DRO Controller  page for more info on supported scales.