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- A flashing circuit with two timers: A Retentive Timer does not reset each time the Enable turns off. The ACC (accumulated value) remains unchanged. To turn off a Retentive Timer, a RES (Reset) coil must be energized. Along with timers, counters are introduced to provide counting functions similar to mechanical counters. Function blocks allow inputs from the left and pass power through to the right when the counting function is done. When done, the counter has counted to the preset. Preset (PRE) and Accumulated (ACC) values can be modified on-line as well as offline. These values are adjusted many times after the program is running in order to eliminate any wasted time in the cycle of a machine. To move a preset from .50 to .05 second can save hundreds or even thousands of dollars in added productivity of a machine over a year’s time. As a rule, these timers are set to the lowest possible value to not damage the machine or cause a problem. 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
