The LCD allows you to view and change the data value of an integer file. You can access to this functionality via the Monitoring screen of the LCD.
To monitor an integer file on the LCD, you have to specify its file number in the Target User Defined File Number (TUF) element of the LCD Function File and download your application program to the controller. The TUF element can only be changed by a program download.
The value stored in the TUF element identifies the integer file with which the LCD will interface. Valid integer files are N7, and N10 through N255. When the LCD reads a valid integer file number, it can access up to 256 bits (0…255) on the LCD screen. The protection bit (LCD edit disable) in the data file properties of the target integer file are used to define the read-only or read/write privileges for its file.
Valid file type include Bit, Integer, Double integer or Float, as specified in the TUF element.
The example table below shows how the LCD uses the configuration information with integer file number 7 (LCD:0.TUF=7).
The data protection for its file depends on the setting for LCD Edit Disable. If LCD Edit Disable is set to 1 in file properties, the corresponding data file is considered read-only by the LCD and the “Protected!” message is displayed.
For explanations in this section, we assume the following in the application program:
• An integer file N7, which is 256 elements long (256 words), is defined with the preset data, as shown in the screen capture below.
IMPORTANT Use your programming software to ensure that the integer file you specify in the TUF element, as well as the appropriate number of elements, exists in the MicroLogix 1400 user program.
IMPORTANT Although you cannot change protected data from the LCD keypad, the control program or other communication devices have access to protected data. Protection bits do not provide any overwrite
protection to data within the target integer file. It is entirely the user’s responsibility to ensure that data is not inadvertently overwritten.
TIP The LCD always starts at word 0 of a data file. It cannot start at any other address within the file.
• The TUF element of the LCD Function File is set to 7 to specify the integer file N7 as the target integer file to monitor on the LCD, as shown in the screen capture below.
• The controller mode is set to REMOTE RUN.
Follow these steps to view and change the data values of the integer file N7.
1. On the Main Menu screen, select Monitoring by using the Up and Down keys on the LCD keypad.
2. Press the OK key on the LCD keypad. The File Number prompt is displayed.
3. If Integer is selected, as shown in step 2, press the OK key.
4. The current data value (ON) of the N7:0 word is displayed. Note that the target word “0”, which is right next to “N7:”, is flashing, which means the cursor is at the target word position.
5. We will change the data value of the N7:0 word to the negative decimal value -1300. First, press OK to move the cursor to the data value position. Then, the last digit of “+00000” will be flashing, which means the cursor is at the data value position.
6. Press the Left key twice. Then, the cursor will position at the third digit. Press the Up key three times to change the third digit to 3.
7. Press the Left key once. Then, press the Up key once. The second digit will change to “1”. Note that “1” is still flashing, which means the cursor is still at the data value position.
8. Press the Left key once. Then, press the Down key once. The sign digit will change to “-”, as shown below. Note that “-” is still flashing, which means the cursor is still at the data value position.
9. Press OK to apply the changes. Then, the new value -1300 is applied. Note that the target word “0”, which is right next to “N7:”, is flashing. The cursor is moved automatically to the target word position.
You can identify this change of data value is reflected to your RSLogix 500/RSLogix Micro programming software, as shown below.
TIP After changing the data value of a target word, press the OK key to apply the changes or press the ESC key to discard the changes.
10. Now, we will view an example of the data value of a protected property. If LCD Edit Disable is set to checked (enable), the “Protected!” message will be displayed and this data file cannot be edited by the LCD.
11. Try to move the cursor to the data value position by pressing the OK key. Because the N7:0 word is protected, you will find that the cursor even does not move to the data value position.
12. If you have finished monitoring the integer file N7, press the ESC key to return to the Main Menu screen, as shown in step 2.