Debug a Plan

Find and fix issues in your OPAL Plans using built-in debugging tools.

Pro Tip

Add log() statements liberally during development - they're your best friend for understanding plan behavior. You can always remove them or change to log_debug() for production use.

Debugging tools

OctoMY™ provides several debugging features:

Using log output

Adding log statements

plan DebugExample {
    loop {
        var distance = sensors.distance.front
        log("Distance reading: " + distance + "cm")

        if distance < 30 {
            log("WARNING: Obstacle detected!")
            log("Taking evasive action")
            avoid_obstacle()
        }

        delay(100)
    }
}

Viewing logs

Open the log panel while plan is running:

Log levels

log("Normal message")           # INFO level
log_debug("Debug details")      # DEBUG level (verbose)
log_warn("Warning message")     # WARNING level
log_error("Error occurred!")    # ERROR level

Filter logs by level in the UI dropdown.

Variable watch

Monitor variable values in real-time:

Enable watch

1. Click [Debug] button
2. Select Variable Watch
3. Add variables to watch list

Watch expressions

Watch calculated values:

Breakpoints

Pause execution at specific lines:

Set a breakpoint

Click the line number in the editor:

Breakpoint controls

When paused at a breakpoint:

Step execution

Run your plan line by line:

Start step mode

1. Click [Debug] → [Step Mode]
2. Plan starts paused at first line
3. Click [Step] to advance

Sensor monitor

View live sensor data while debugging:

Common errors

Syntax errors

Error at line 5: Unexpected token '}'

Solution: Check for missing brackets, parentheses, or semicolons.

# Wrong
if distance < 30
    avoid_obstacle()
}

# Correct
if distance < 30 {
    avoid_obstacle()
}

Undefined variable

Error at line 7: Variable 'distanc' is not defined

Solution: Check variable spelling.

# Wrong
var distance = 50
if distanc < 30 {  # Typo!

# Correct
var distance = 50
if distance < 30 {

Type mismatch

Error at line 4: Cannot compare string to number

Solution: Ensure types match in comparisons.

# Wrong
var state = "running"
if state < 30 {  # String vs number!

# Correct
var state = "running"
if state == "running" {

Sensor not found

Error: Sensor 'distance.rear' not found

Solution: Verify sensor name and that hardware is configured.

# Check available sensors first
log(sensors.list())

Performance issues

Plan running slow

Cause: Loop running too fast without delay.

# Bad - uses 100% CPU
loop {
    check_sensors()
    # No delay!
}

# Good - runs at 20Hz
loop {
    check_sensors()
    delay(50)  # 50ms between iterations
}

Memory issues

Cause: Creating objects in loop without cleanup.

# Bad - memory grows forever
loop {
    var data = read_all_sensors()  # New object each loop
}

# Good - reuse variable
var data = {}
loop {
    data = read_all_sensors()  # Replaces old value
}

Debugging state machines

For complex plans with states:

plan StateMachine {
    var state = "idle"
    var prev_state = ""

    loop {
        if state != prev_state {
            log("State change: " + prev_state + " -> " + state)
            prev_state = state
        }

        if state == "idle" {
            # ...
        } else if state == "searching" {
            # ...
        } else if state == "avoiding" {
            # ...
        }

        delay(50)
    }
}

State history

Enable state logging:

Remote debugging

Debug plans from a connected Remote:

1. On Remote: ☰ Menu → Utilities → Plan Debug
2. Select the Agent and Plan
3. Access all debugging tools remotely

Debugging tips

1. Start simple - Get basic behavior working first
2. Log generously - More logs = easier debugging
3. Test sensors first - Verify readings before using them
4. Use watch - Monitor key variables continuously
5. Check edge cases - What if sensor reads 0? 999?
6. Isolate problems - Comment out code to find issues
7. Version control - Save working versions before changes