Single lane Parking example using Timer | PLC programming | Part 17

Basics of PLC timer- PLC timers are instructions that provide the same functions as on-delay and off-delay mechanical and electronic timing relays. A PLC timer provides a preset delay to the control actions. In general, there are three types of PLC timer delays, ON-delay timer, OFF-delay timer and retentive timer on. The terms represented in the timer block in the PLC are a Preset value which means the delay period of the timer, an Accumulated value which is the current delay of the timer. A timer begins the counting on time-based intervals and continues until the accumulated value equals the preset value. When the accumulated value equals the preset time the output will be energized. Then the timer sets the output. Timer example:- Single lane parking – Control Purpose: The Entry/Exit of the parking lot is a single lane passage. By controlling the indicators, the program ensures that only one car can pass through the Entry/Exit so as to prevent car accident between entering and leaving cars. Devices & Function X0:- Car entering sensor. When a car passes through the sensor, X0 = ON. X1:- Car leaving sensor. When a car passes through the sensor, X1 = ON. Y0:- Entering car indicator (ON means “GO”, OFF means “STOP”） Y1:- Leaving car indicator (ON means “GO”, OFF means “STOP”) Program Description: In the parking lot, there are two indicators individually directing the entering and leaving cars. By the interlock control circuit, only one indicator will show “GO” signal and the car accident will thus be prevented. When an entering car draws near the vehicle control barrier, X0 will be ON and so will Y0. The entering car indicator will show “GO”. At the same time, the leaving car indicator will show “STOP.” Car entering is allowed but leaving is prohibited in this case. When a leaving car draws near the vehicle control barrier, X1 will be ON and so will Y1. The leaving car indicator will show “GO” and the entering car indicator will show “STOP.” Follow Us On : Google Reviews : https://goo.gl/LxpEsU Facebook : https://www.facebook.com/wscubetech.india Twitter : https://twitter.com/wscube Linkedin : https://www.linkedin.com/company/wscube-tech Google + : https://plus.google.com/+wscubetechjodhpur Youtube : https://www.youtube.com/c/wscubetechjodhpur Website : http://wscubetech.com