If the door is currently opening, pressing the Close Switch will immediately halt movement.In this exercise we want you to modify your program so that it adheres to this additional criteria: We do not recommend proceeding with this exercise if you do not have an instructor or experienced PLC programmer to call upon for assistance.
Quote: Supplemental Programming Exercise #4: This can be reduced down to more consise logic this way: IF T4:1.ACC is LESS THAN 140, then turn on N/S Red light. Rung 2, N/S Red light: Branch 1 says IF T4:1.ACC is LESS THAN or EQUAL to 20, OR (Branch 2 says) IF T4:1.ACC is GREATER THAN 10 OR LESS THAN 140, then turn on light. Third, some of your comparison logic is a little flaky. Think about it some, then if you can't solve it, look at the attached LogixPro program. I am sure that many pedestrains would curse your soul if such a scheme was actually used! You need to come up with a way to save a button-push for use later in the cycle. Your method so far for the Walk depends upon a pedestrian pushing the button when the Timer T4:0 is at a certain stage (E/W Amber On, or N/S Amber Not On). Second, your walk light logic needs to be designed so that a pedestrian can walk up AT ANY TIME and push the Walk button.
Delete either rung 8 or 9 for the O:2/3 E/W Walk Light. First off, you should not normally have two rungs with the same digital output (redundant outputs).
