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. Basic PLC Ladder Programming Training Example- This is PLC program for an artificial fishpond water level monitoring system. Problem Solution This problem can be solved by using simple automation. Here we considered one artificial fishpond, four level sensors and three pumps for system monitor & control. Here we will write program that will control whole system. System will maintain normal level and it does not allow water level to go up or down to maintain the normal level. If water level goes down from the normal level then system will feed water in the fishpond and if water level goes up from the normal level then system will drain water from the fishpond. Program Here is PLC program for an artificial fishpond water level monitoring system. List of Inputs/Outputs Inputs List:- Level Sensor, L0 = I: 0.0 (L0=1 when the water level is above the alarm level). Level Sensor, L1 = I:0.1 (L1=1 when the water level is above the normal level) Level Sensor, L2 = I:0.2 (L2=1 when the water is above the normal level) Level Sensor, L3 = I:0.3 (L3=1 when the water is above the alarm level) Outputs List:- Feeding pump :- O:0.0 Drainage pump 1 :- O:0.1 Drainage pump 2 :- O:0.2 Alarm lamp :- O:0.3 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
