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- Sequential delay example- Starting 3 Motors Sequentially with delay i.e. starting the oil pump motor immediately when START is pressed. The main motor will be started after a 10 sec delay and then the auxiliary motor after a 5 sec delay. In addition, stopping all motors immediately when STOP is pressed.PLC Timer (Starting 3 Motors Sequentially). Number of PLC Inputs Required X1 – Start Switch.      X2 – Stop Switch. Number of PLC Outputs Required Y0 – OIL Motor Y1 – Main Motor Y2 – Auxiliary Motor Number of PLC Timer Required T0 – 10 second Timer, 100 ms Time Base. (See K100 Preset Value for Timer) T1 – 5 second Timer, 100 ms Time Base. (See K50 Preset Value for Timer) PLC Ladder Program Description: •        When START is pressed, the NO contact X0 will be activated, which makes Y0 to be ON and latched. The oil pump motor will start the lube system. At the same time, [TMR T0 K100] instruction will be executed. When T0 reaches its set value of 10 sec, the NO contact T0 will be ON.   •        When the NO contact T0 is ON, Y1 will be ON and latched, which starts the main motor and stops timer T0. At the same time, [TMR T1 K50] is executed, and the NO contact T1 will be ON when timer T1 reaches its set value. •        When the NO contact T1 is ON, Y2 will be ON and latched, which starts the auxiliary motor and stops T1.   •        When STOP is pressed, the NC contact X1 will be activated, which makes Y0, Y1 and Y2 OFF. The oil pump motor, main motor and auxiliary motor will stop working. 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
