Input/output

tip

Output signals cannot be set directly. Instead, conditions are tied to actual output pins using the printer settings, and the API sets the conditions.

GPIO conditions you define from the API come in two kinds v5.0:

• User conditions — named boolean values set directly with setGpioConditions. They persist across restarts, are listed with listUserGpioConditions, and removed with removeUserGpioCondition.
• User expressions — named boolean expressions derived from other conditions, managed with setUserGpioExpressions, listUserGpioExpressions, and removeUserGpioExpression.

Use listGpioConditions for the current state of every condition and expression, and listWritableGpioConditions for the conditions whose state can be set via the API.

Built-in conditions

Besides the conditions and expressions you define, the system maintains read-only built-in conditions that reflect printer status. Each printer exposes its own conditions named printer.<printerID>.<name> (for example printer.Colorize.printing), and matching aggregate conditions named printers.<name> combine that condition across all printers (for example printers.printing). Use listGpioConditions to see which conditions are available.