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Enter Ladder Logic

Ladder Logic​

CICON offers ladder diagram language for making PLC projects. Ladder logic is entered in Scan programs.

Basic Ladder Diagram Composition​

  • Standard ladder diagram Scan programs will look like the diagram above:
    • Step Amount:
      • Each contact, coil, instruction, etc., cost a certain amount of steps.
      • The step number for the rung is listed on the far left of the rung (highlighted in dark blue).
    • Invalid Rung:
      • Incomplete rungs or invalid rungs that are added to the program, but not saved, will show a red vertical line on the far left of the rung.
      • This rung is incomplete since there is no resulting condition attached to the normally open contact M0.1 (highlighted in red).
    • Rung Number:
      • Each new and separate rung will display the rung number with the notation R.# on the far left of the rung (highlighted in gray).
    • Valid Rung:
      • New and complete rungs will show a green vertical line on the far left of the rung (highlighted in green).
    • Unsaved Rungs:
      • Any rung that has been added to a Scan program, or any rung that has a change made to it and has not been saved, will appear highlighted.
        • In this example, the top 3 rungs are highlighted in light blue.
    • Instruction:
      • Instructions added to the Scan program will typically have a black box around them while listing the instruction name and operands, if any (highlighted in red).
    • Execution Condition (Input) → Result Instruction (Output):
      • Typically in ladder logic, execution occurs from left to right.
      • An execution, input button for example, triggers, and the resulting output, light for example, energizes (light lights up).

Add Rungs​

  1. To add more rungs to the ladder diagram, left-click the rung where new rungs will be added. New rungs will be added ABOVE the selected rung.

  2. Type CTRL + L to insert a new rung.

  • If changes have been made to the ladder diagram, the changed rung will appear as a different color.

  • Additionally, the program title will have an asterisk, *, next to the name.
    • This means the program has NOT been saved since recent changes were made.

  • Alternatively, to insert a new rung, left-click Edit and left-click Insert Row.

  1. To insert a rung below the currently selected rung, left-click the rung and type CTRL + Enter.

  • The new rung will be inserted below the selected rung.

  • Alternatively, to insert a rung below the selected one, left-click Edit and left-click Insert Next Row.

Columns​

Enable/Disable Columns​

  1. Columns can be added to the ladder logic program. To enable or disable column view, left-click View and left-click LD Grid to toggle columns on or off.

Change Column Size​

  • The amount of columns per rung can be increased or decreased.

  1. To change the amount of columns, left-click View and left-click Change LD Col.

  1. Specify the number of columns to display per rung.

    • Minimum: 9
    • Maximum: 80
    • Default: 11

  2. Left-click OK.

  • The number of columns will change.

Toolbar and Tools​

  1. To use the ladder logic toolbar, left-click View.

Arrow​

  • The arrow tool will restore the mouse cursor if it is being occupied by another CICON component.

Erase​

  • The erase tool will delete the components of the ladder diagram.

Erase Tool​

  1. Left-click on the component to delete.

  2. On the toolbar, left-click Erase.

    • Optionally, use the DELETE key on the keyboard.

  • The erased component will be deleted.

Vertical Line​

  • The vertical line tool will create a vertical line between rungs.

Vertical Line Tool​

  1. Left-click the rung to add the top of the vertical line.

    • This will connect the currently selected rung with the below rung.

  2. On the toolbar, left-click the Vertical Line icon.

    • Optionally, type SHIFT + F2 or CTRL + DOWN ARROW.

  • A vertical line will be placed in front of the open contacts.
    • The lower of the rungs is no longer invalid.
  • This creates a basic OR gate connection.

Delete Vertical Line​

  • The delete vertical line tool will remove a vertical line connecting two rungs.

Delete Vertical Line Tool​

  1. Left-click the space next the component to delete the connecting vertical line.

  2. On the toolbar, left-click the Del Vertical Line icon.

    • Optionally, type CTRL + F2 or left-click below rung and type CTRL + UP ARROW.

  • The two rungs will no longer be connected.

Horizontal Line​

  • The horizontal line tool will create a horizontal line in the same rung.

Horizontal Line Tool​

  1. Left-click a space in the ladder diagram.

  2. On the toolbar, left-click the Horizontal Line icon.

    • Optionally, type F2, CTRL + LEFT ARROW or CTRL + RIGHT ARROW.

  • Individual horizontal lines will be added into the ladder diagram.

Invert​

  • The inversion tool will insert an inversion component to invert the signal from an execution condition.
    • If the signal from the execution condition is OFF (0), the resulting output will energize/be ON (1).
    • If the signal from the execution condition is ON (1), the resulting output will deenergize/be OFF (0).

Invert Tool​

  1. Left-click the space to place the inversion.

  2. On the toolbar, left-click Invert.

    • Optionally, type F4.

  • The inversion signal will show a red slash through the middle of a horizontal line.

Normally Open Contact​

  • The normally open contact tool will place a normally open contact in the ladder diagram.
    • While ON (1), normally open contacts receive a continuous source of power and execute the resulting operation until powered OFF (0).
      • The resulting operation will be executed many times per scan.
    • For more information, refer to open contacts.

Normally Open Contact Tool​

  1. Left-click the rung to insert a new normally open contact.

  2. On the toolbar, left-click Contact A.

    • Optionally, type F5.

  1. Enter the data register and left-click OK.

  • The open contact will be added to the rung.

  • Multiple normally open contacts can be added to a rung.
    • The creates a basic AND Gate connection.

Normally Closed Contact​

  • The normally closed contact tool will place a normally closed contact in the ladder diagram.
    • While OFF (0), normally closed contacts output a continuous source of power and execute the resulting operation until powered ON (1).
      • The resulting operation will be executed many times per scan.
    • For more information, refer to closed contacts.

Normally Closed Contact Tool​

  1. Left-click the rung to insert a new normally closed contact.

  2. On the toolbar, left-click Contact B.

    • Optionally, type F6.

  1. Enter the data register and left-click OK.

  • The closed contact will be added to the rung.

  • Multiple normally closed contacts can be added to a rung.
    • The creates a basic AND Gate connection.

Positive Transition-Sensing Contact​

  • The positive transition-sensing contact tool will place a positive transition-sensing contact in the ladder diagram.
    • The resulting operation will be executed once each time the contact receives power.
    • The execution condition is executed on the rising edge of a pulse.
    • For more information, refer to rising edge contacts.

Positive Transition-Sensing Contact Tool​

  1. Left-click the rung to insert a new positive transition-sensing contact.

  2. On the toolbar, left-click Pulse Up.

    • Optionally, type F7.

  1. Enter the data register and left-click OK.

  • The positive transition-sensing contact will be added to the rung.

  • Multiple positive transition-sensing contacts can be added to a rung.
    • The creates a basic AND Gate connection.

Negative Transition-Sensing Contact​

  • The negative transition-sensing contact tool will place a negative transition-sensing contact in the ladder diagram.
    • The resulting operation will be executed once each time the contact receives power.
    • The execution condition is executed on the falling edge of a pulse.
    • For more information, refer to falling edge contacts.

Negative Transition-Sensing Contact Tool​

  1. Left-click the rung to insert a new negative transition-sensing contact.

  2. On the toolbar, left-click Pulse Down.

    • Optionally, type F8.

  1. Enter the data register and left-click OK.

  • The negative transition-sensing contact will be added to the rung.

  • Multiple negative transition-sensing contacts can be added to a rung.
    • The creates a basic AND Gate connection.

Coil​

  • The coil tool will create a coil ad the end of a rung.

Coil Tool​

  1. Left-click on any space in the rung.

  2. On the toolbar, left-click Coil.

    • Optionally, type F9.

  1. Enter the data register and left-click OK.

  • The coil will be placed at the end of the rung.
    • Only one coil can be placed per rung.
    • It is advised to have only one occurrence of each coil per scan program.

Application Instruction​

  • The application instruction tool will insert an application instruction into the ladder diagram.
  • Most application instructions will execute a command/instruction when the execution condition is true.

Application Instruction Tool​

  1. Left-click on any space in the rung.

  2. On the toolbar, left-click Application Instruction.

    • Optionally, type F10, or type any character on the keyboard.

  • The application instruction window will appear.
  1. Type the name of the instruction in the Instruction tab, or select the instruction category on the left and instruction on the right.

  • The instruction format will appear in the Instruction tab.

  1. Select the data registers required for the instruction.

  2. Left-click OK.

  • Optionally, left-click Basic for a basic view of the instruction list.

  • Left-click Details to return to the previous view.

  • The instruction will appear after the execution condition.

Comment​

  • The comment tool will insert a comment into the ladder diagram for organizational use.

Comment Tool​

  1. Left-click on any space in the rung.

    • The comment will be placed above the currently selected rung.

  2. On the toolbar, left-click the Comment icon.

    • Optionally, type F12.

  1. Enter the comment into the Input Comments window.
    • To enter a new line, type CTRL + ENTER.
  • To add a date to the comment, left-click Add Date.
  • To add a row of asterisks (*), left-click ********.
  • To add a row of dashes (-), left-click --------.
  • To change the color of the comment, left-click Color.
  • To add the comment as a historical comment to use elsewhere, left-click Add Cmt.
  1. Left-click OK.

  • The comment will appear above the rung.

Add Function Block​

  • The add function block tool will insert a function block into the ladder diagram.

Add Function Block Tool​

  1. Left-click on any space on the rung.

  2. On the toolbar, left-click Add FB.

    • Optionally, type SHIFT + F9.

  1. Left-click a function block group.

  1. Left-click a function block.

  • The function block requirements will appear in the FB Preview window.
  1. Left-click OK.

  • The function block will appear in the ladder diagram.
  1. Double left-click on the function block to edit the data registers.

  1. Enter the data registers under the Device tab.

  2. Left-click OK.

  • The function block will now display the data registers.

Save Program​

  1. To save the program, left-click Home and left-click Save All.

  • Optionally, left-click Project and left-click Save Program.