Function block diagram program inputs and outputs

In an FBD program, each input variable must be connected to a block input and the data type of the input is correct. A block input can be a literal value, an internal variable, an input variable, or an output variable from another block.

Each output variable must be connected to a block output and the data type of the output is correct. A block output can be an internal variable, an output variable, or the name of a block (for functions only). If the output is the name of an edited function, the output represents the assignment of the return value for the function, and the output value is returned to the calling program.

Variables, inputs, and outputs in an FBD program are connected or wired using connection lines or links. You can connect any of the following logical points in an FBD diagram using a single line:

Connections are oriented from left to right, carrying data from left to right. The left connection and the right connection must be of the same data type.

A single left connection point can be connected to multiple right connections, called divergences, to broadcast information to multiple points. All connections must be of the same data type.