In

QFIRE Studio

, there are Shared Variable I/Os, Goto, and From blocks. They can look the same but they are very different, some differences are:

• The scope of a Shared Variable is universal amongst Tasks, any level of Hierarchical State Machines and Subsystems.
• The scope of Goto and From blocks is signal flow local. It is restrained to a single Finite State Machine or a Task without State Machines.
• Shared Variables use true storage entities in the target controller.
• Goto and From blocks do not exist in the target controller. They are just signal routing resources.

Shared Variable

Shared Variables are executed by the blocks in Figure 1. They work like virtual I/Os in a diagram. They can exchange signals amongst Hierarchical State Machines and tasks.

The connection is defined by the variable index as can be seen in the tab in Figure 2. It is possible to use up to 128 variable indices. The indices are universal: when a Shared Variable Output with the variable index 0 receives a signal, all Shared Variable Inputs with the same variable index can access this signal.

Goto and From

Similar to the Shared Variable blocks, Goto and From blocks work like a virtual connection. The connection of Goto and From is merely a visual connection used to simplify a diagram. In other words, adding Goto and From blocks has no impact in computation time. They only exist in the IDE of

QFIRE Studio

, not in the code embedded into the

QFIRE

.

The connection between Goto and From blocks are defined by the Goto Name field. The Goto Name can be made of numbers or words. It's possible to create as many as you need.

The connection is completed when the Goto Name is selected in the From Block as can be seen in Figure 5.

Blocks in different tasks (or Finite States) with the same Goto Name do not work like Shared Variables. It means that Goto and From blocks are constrained to its signal flow scope. Its extent is the widest possible in its current signal flow scope, i.e. can be accessed and assigned inside multiple subsystems.