MATH FUNCTIONS

ADD - Addition
The ADD functions sums all the inputs (Px) together and outputs this number (O). The number of inputs is specified when the function is placed in the program. The enable (EN) must be true for the ADD function to be enabled. The Q output is true when the ADD function is enabled.

1. We will now use the ADD function in a ladder diagram.
2. Place EZ LADDER® in the Edit mode (if in the Monitor mode).
3. Close any currently open ladder diagrams (save them if necessary).
4. Create a NEW ladder diagram Project.
5. Configure the target as follows: (if you use a different target, some of the features may not be available)
   1. PLC on a Chip, Model PLCHIP-M2-25631
   2. Install Digital Inputs : GPI0 - GPI7
   3. Install Digital Outputs : GPO0 - GPO7
   4. Install Analog Block Analog Block 0
   5. Install the Real Time Clock
   6. Install the SSI Bus
6. Using the Insert Function drop down menu on the tool bar, select ADD.
7. Place the cursor on Rung 1 near the center of the ladder diagram workspace and left-click to place the object. The Functions properties dialog box will appear. Set the number of inputs to 3 and click OK. The ADD is now placed.
8. Select the DIRECT CONTACT button from the tool bar.
9. Place the cursor on Rung 1 near the left power rail and left-click to place the contact. The Contact properties dialog box will appear. Using the drop down menu in the dialog box, selct GPI0 and click OK. This finishes the placement of the contact that is tied directly to hardware input GPI0 (also named GPI0).
10. Select the DIRECT COIL button from the tool bar.
11. Place the cursor on Rung 1 near the right power rail and left-click to place the contact. The Coil properties dialog box will appear. Using the drop down menu in the dialog box, selct GPO0 and click OK. This finishes the placement of the coil that is tied directly to hardware input GPO0 (also named GPO0).
12. Select the HORIZONTAL LINK tool.
13. Draw a link from the right side of the GPI0 contact to the EN input on the ADD function.
14. Draw a link from the Q output of ADD to the left side of the GPO0 coil.
15. We now need to insert variables to give the ADD its parameters and output. Select the INST VARS button from the tool bar.
16. Place the cursor on Rung 2 just left of the P1 input on ADD. Left-click to insert the variable. The Variables dialog box will appear. Select the INTEGER tab.
17. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Num1 for the Name, select INTERNAL as the variable type and set the DEFAULT VALUE to 5, then click OK. This is the the first of the numbers to add together.
18. With the INST VARS still selected, place the cursor on Rung 3 just left of the P2 input on ADD. Left-click to insert the variable. The Variables dialog box will appear. Select the INTEGER tab.
19. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Num2 for the Name, select INTERNAL as the variable type and set the DEFAULT VALUE to 25, then click OK. This is the last of the number to add together.
20. With the INST VARS still selected, place the cursor on Rung 2 just right of the O output on ADD. Left-click to insert the variable. The Variables dialog box will appear. Select the INTEGER tab.
21. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Sum for the Name, select INTERNAL as the variable type and leave the DEFAULT VALUE blank, then click OK. This is sum of the numbers will be output to.
22. Save the ladder diagram from the File menu and selecting SAVE. It is a good idea to periodically save your ladder diagram when developing it.
23. Compile the target using the COMPILE button from the tool bar. Ensure that the compile is successful and there are no errors. If there are errors they must be corrected. Your ladder diagram should look similar to this:



24. We are now ready to run the program on the target. Switch to the Monitor mode by clicking the MON button from the tool bar.
25. Connect to the target, by selecting the CONNECT button from the tool bar. If a different program is running, just click OK.
26. Download the ladder diagram to the target by selecting the DOWNLOAD button from the tool bar. If successful, the ladder diagram is now operating on the target. It should look similar to:



27. Close the switch connected to Input 0. GPI0 is true causing power flow. The GPO0 output will be true (showing power flow). The variable "Sum" connected to the ADD O output is now displaying the sum of the two numbers (30).
28. Open the switch connected to Input 1. GPI1 is false causing no power flow. The GPO0 turns false(showing power flow).

You have completed the ADD exercise.