Objective-
The objective of this lab is to create a traffic intersection using the Allen-Bradley plc and RSlogix software. Two traffic lights are used for North-South, one turn and one thru, and one light is used for East-West. These should be programmed to allow one lane green and the others red, with working yellow lights. N-S lanes should blink yellow and E-W lanes should blink red in night mode. A push button for a crosswalk is to be added where all lights turn red, and then continue after a given amount of time.
Results-
After programming this traffic intersection in RSlogix, we successfully created a basic traffic intersection program with a night mode and crosswalk push button. Each Green-Red-Red rotation lasts 5 seconds, and each Yellow-Red-Red lasts 2 seconds. Between midnight and 7 am (rung 29), this enables. While night mode is on, both North-South lane lights flash yellow every second, which means East-West lane light will flash Red each second. While yellow is on, Red is off and while Red is on, yellow is off. This will lower power at one given time (so all aren't on at same time). The last screenshot shows a subroutine with the flashing timers as well as the time-date logic.
This program also has a pedestrian cross walk push button. This allows 10 seconds for pedestrians to cross while all lights are red. When the push button is pressed, the normal rotation still continues until the next light that will turn red, turns red. All lights will turn red for 10 seconds and will also turn on a crosswalk light. After 10 seconds, the program will continue to where it left off. Since output coils can't be used more than once, we had to put in NEQ logic so these outputs could be used more than once for each condition.
Conclusions-
After constructing this lab in the program and wiring it, we were successfully able to connect the plc to the computer and test this using push button lights for outputs for every scenario, as well as a push button for the crosswalk. it was expected to allow 5 seconds for green/red conditions and 2 seconds for yellow conditions.
A one-shot was used (rung 27) so even if this push button was held, it wouldn't stay latched. We had to go into the Date_Time bits and manually change the time to between midnight and 7 am. When we did, N-S lanes successfully flashed yellow and E-W lane flashed red. The first 3 rungs of logic are just to show outputs which will go green while they are energized in the program.