Chapter 7 Function Block and Library Set TRIG_1 to OFF. Open the window for ET_INS_1 . TRIG in the window remains ON. This indicates that the states of the symbols in a function block will be retained after the function block is executed. Open the window for ET_INS_2 . TRIG in the window is OFF. The state of TRIG in the window for ET_INS_2 is different the state of TRIG in the window for ET_INS_1 . This indicates that the function block instances operate independently. After the users follow the steps above, they can draw the following conclusions. 1. If the flag connected to the En pin of a function block is OFF, the program in the function block will not be executed. 2.
The states of the symbols in a function block will be retained after the function block is executed. 3. The function block instances in a project operate independently. Obviously, the execution of the program in this section is different from the execution of the program in section 6.3. In the program in section 6.3, TRIG_1 is OFF when the flag RUNNING is OFF. In the program in this 7-47