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#Siemens simatic s7 training simulator
COMMAND must be inactive while OUTPUT must be active, this combination guarantees the timer starts only after COMMAND has already been ON and then turned OFF again.ĭid you test it on your simulator yet? Works like a charm. Second rung is the timer rung it simply shows the condition that must exist before the timer should start counting the 3 seconds preset value. The first rung is a simple once the COMMAND is active the OUTPUT will turn ON immediately, the OUTPUT is self-latched so when the COMMAND is no longer active, OUTPUT stays ON, until the output of the ON DELAY timer “TM1.OUT” is active, that will cut the line feeding OUTPUT and so de-energize it.
#Siemens simatic s7 training how to
Turning ON the output is similar to a normal relay, it happens immediately.īelow is a ladder diagram that shows how to derive the above OFF DELAY timing function by utilizing an ON DELAY timer. OFF DELAY TimerĪn OFF DELAY Timer is similar to a relay, except it “ turns the output OFF after a certain DELAY”, and that’s how it got its name, OFF DELAY. In a ladder diagram, the use of an ON DELAY timer block is very simple, the block receives a COMMAND, and after the preset time has elapsed, the timer output contacts (TM1.OUT) are switched, turning our OUTPUT ON or OFF.Īs in the ladder diagram above, all-over this post we are going to use the term COMMAND to indicate the condition to start the timing function, the term OUTPUT to indicate the result of the timing function, and TON DELAY for ON DELAY timer blocks. Turning off the output is similar to a normal relay, it happens immediately. The Master of All the Timers! ON DELAYĬompared to a normal relay, a relay is a device that switches its outputs (ON or OFF) immediately with the changes with its input state.Īn ON DELAY Timer on the other hand, is similar to a relay, except it “ turns the output ON after a certain DELAY”, and that’s how it got its name, ON DELAY. Here we will show examples of deriving three types of timers (or timing functions):īefore we show how, let’s take a look at how the ON DELAY timer works. Practically, you can derive any type of timer or timing function, by correctly utilizing the most basic type of timer, the ON DELAY. But dancing around the timer “types” as a selling point just seemed misleading to me. As much as the words sound tempting, from a practical point of view, these 7 types have no real value, except for the very lazy PLC programmers.ĭon’t get me wrong, timing and sequencing are key functions in any control system, I can easily assume there is no control application that doesn’t contain at least one timer. Lately I’ve been reading some PLC brochures, I noticed one vendor bragging that his smallest PLC provides 7 types of timers and timing functions, presenting this as a differentiating factor between his PLC and the other brands.