logi.CAD 3 supports the following types of step sequences to be created within the →graphical FBD-editor:

Single step sequence
Step sequence with divergence and convergence
Step sequence with simultaneous divergence and simultaneous convergence

Single step sequence

Step sequence with: initial step, step, transitions, action blocks

How to create this step sequence:

Create the initial step, the step and the transitions.
See "Creating or editing initial steps or steps in FBD" and "Creating or editing transitions in FBD" for details.
Connect the initial step with the successor by a line.
See "Connecting FBD-elements by lines" for details.
Likewise, connect the transition with the successor step by a line and connect the step with the next transition.
If required: Create some action blocks.
See "Creating or editing action blocks in FBD" for details.
Connect one input of an action block to the output of the initial step and the input of the other action block to the output of the step.

If necessary, create more steps, transitions, action blocks and connect them as well.

Step sequence with divergence and convergence

A divergence exists, when several transitions follow one step.
A convergence exists, when one step follows several transitions.

You might know divergences and convergences as alternative branches and alternative junctions.

images/download/attachments/414777514/Sequence2_EN-version-1-modificationdate-1534165106805-api-v2.png

Create such step sequences by connecting the step to one transition, by creating a connection point on the existing line (see "Creating a line fork (incl. a connection point)" for details) and by connecting the next transition to the connection point.
If you do not need the divergence or the convergence any longer, just delete the connection point or the appropriate lines (see "Deleting FBD-elements or already declared variables" for details).

Example for creating a divergence:

Connect step S0 with the left transition.
Create the connection point on the line.
Create the line from the connection point to the other transition.

Example for creating a convergence:

Connect the left transition with step S3.
Create the connection point on the line.
Create the line from the connection point to the other transition.

Step sequence with simultaneous divergence and simultaneous convergence

A simultaneous divergence exists, when several steps follow one transition.
A simultaneous convergence exists, when one transition follows several steps.

You might know simultaneous divergences and simultaneous convergences as parallel branches and parallel junctions.

Deviations from IEC-standard

The lines for simultaneous divergences and simultaneous convergences are represented as dotted lines by logi.CAD 3. This is in contrast to the IEC-standard where a double horizontal line is specified.

images/download/attachments/414777534/Sequence3_EN-version-2-modificationdate-1534165311366-api-v2.png

Create such step sequences by connecting a step to the transition, by creating a connection point on the existing line (see "Creating a line fork (incl. a connection point)" for details) and by connecting the next step to the connection point.
If you do not need the simultaneous divergence or the simultaneous convergence any longer, just delete the connection point or the appropriate lines (see "Deleting FBD-elements or already declared variables" for details).

Example for creating a simultaneous divergence:

Connect the transition with step S2.
Create the connection point on the line.
Create the line from the connection point to step S1.

Example for creating a simultaneous convergence:

Connect step S2 with the transition.
Create the connection point on the line.
Create the line from the connection point to step S1.