TIME / DATE

GETTIME- Gets the Current Time from the Real Time Clock
The GETTIME function reads the current time from the hardware real time clock. The values of the time are stored into the integer variables on the ouputs. The enable (EN) must be true for the GETTIME function to be enabled.

1. We will now use the GETTIME 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 GETTIME.
7. Place the cursor on Rung 1 near the center of the ladder diagram workspace and left-click to place the object. The GETTIME 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 GETTIME function.
14. Draw a link from the Q output of GETTIME to the left side of the GPO0 coil.
15. We now need to insert variables to give the GETTIME its parameters and output. Select the INST VARS button from the tool bar.
16. Place the cursor on Rung 2 just right of the HR output on GETTIME. Left-click to insert the variable. The Variables dialog box will appear (the only tab available will be the INTEGER tab) since this is connecting to the GETTIME.
17. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Hour for the Name, select INTERNAL as the variable type and leave the DEFAULT VALUE blank, then click OK. This is where the the current hour will be output to.
18. With the INST VARS still selected, place the cursor on Rung 3 just right of the MN output on GETTIME. Left-click to insert the variable. The Variables dialog box will appear (the only tab available will be the INTEGER tab) since this is connecting to an GETTIME.
19. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Min for the Name, select INTERNAL as the variable type and leave the DEFAULT VALUE blank, then click OK. This is where the current minute will be output to.
20. With the INST VARS still selected, place the cursor on Rung 4 just right of the SC output on GETTIME. Left-click to insert the variable. The Variables dialog box will appear (the only tab available will be the INTEGER tab) since this is connecting to an GETTIME.
21. Click the ADD button to add a new variable. The Add variable dialog box will appear. Type Sec for the Name, select INTERNAL as the variable type and leave the DEFAULT VALUE blank, then click OK. This is where the current seconds 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. This will cause the GETTIME function to be enabled.
28. You will now see the current time shown as individual variables connected to the GETTIME function. You will see the time update during each scan.
29. Open the switch connected to Input 0. GPI0 is false which will disable the GETTIME function. The time will no longer be updated because the GETTIME function is disabled.

You have completed the GETTIME exercise.