Ladder Logic Programming Tutorial STEP 4      backbutton.gif (507 bytes)   nextbutton.gif (690 bytes)

We will now create Circuit #2 as shown below.

tutorial1d1.gif (1276 bytes)

  1. Follow the steps listed in STEP 3 to create the following circuit fragment:

tutorial1d2.gif (9065 bytes)

  1. We want to enclose the two series contacts "Step" and Manual" with a parallel branch that contains two elements. First, we will create the branch for the N.C. "Manual" contact.

  2. Click on the element "Step" to highlight it. Then right-click on the   tutorial1c5.gif (209 bytes) icon to create a N.C. parallel circuit that encloses both the "Step" and the "Manual" contacts. A cross will appear at the left hand end of the "Step" contact, indicating that this is the starting location of the parallel circuit. You should now click on the "Manual" contact to select the ending location for the parallel circuit. The yellow highlight bar will be positioned at "Manual" contact now.

  3. You will notice that the tutorial1c5.gif (209 bytes) icon has now changed into a yellow color N.C. contact tutorial1d6.gif (180 bytes) with an opposite connection arm. You should now click on the tutorial1d6.gif (180 bytes) symbol to close the parallel branch. (One possible short-cut method is to double-click at the ending location to close the branch).

    As usual an I/O table will be opened for you to select the I/O. For now, select the "Manual" label from the "input" table to create the following circuit:

tutorial1d3.gif (9261 bytes)    tutorial1d4.gif (6760 bytes)

  1. Next, we want to insert the special bit "Clk:0.5s" to the left of the "Manual" contact. Press the <TAB> key to move the insertion point to the left end of the highlight bar as shown above. Then left-click on the tutorial1c3.gif (330 bytes) icon to create a normally-open contact. Scroll the I/O table to the "Special Bits" table and select the item: "0.5s Clock". The parallel branch would have been completed by now.

Note: The "Special Bit" table comprises some clock pulses and some other special purpose bits. These include the eight built-in clock pulses in the system with periods ranging from 0.01s to 1 minute. Built-in clock pulses are useful if you need a time base to create, for example a "flashing light". A contact such as "Clk:0.1s" will automatically turn itself ON for 0.05s and then OFF for another 0.05s and then ON again, resulting in a series of clock pulses of period = 0.1 second.

  1. Next, move the highlight bar to the right end junction of the parallel circuits as follow:

    tutorial1d7.gif (9799 bytes)

  2. Now, click on the tutorial1c8.gif (219 bytes) icon to insert a special function coil. A popup menu will appear for you to select the desired special function. Click on the item "4.[AVseq]-Advance Sequencer" to insert the Advance Sequencer function [AVseq].

tutorial1d5.gif (7295 bytes)

  1. This function is one that will increment the step counter of Sequencer #1 each time its execution condition goes from OFF to ON.

Again, remember to press the <Enter> key  to complete Circuit #2


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