Function block diagram¶

A routine in FBD is a sheet of blocks wired pin to pin. Inputs are on the left of a block, outputs on the right.

• Add a block from the palette, then drag it into place.
• Wire by dragging from an output pin to an input pin. An output can feed many inputs.
• Operands on pins: an input pin with no wire takes a tag, an address or a constant; an output pin may also write a tag. Drag an I/O point from the simulation onto a pin.
• Instances: timer, counter and PID blocks keep their state in a tag of that type, shown above the block.
• More inputs: AND, OR, ADD… take more inputs (right-click → Add input).

Blocks run in data-flow order: a block runs after every block wired to its inputs. A loop of wires is reported as an error.

Online, every pin shows its live value and BOOL wires turn green when TRUE.

See the block reference.