Timer status bit in S7

[dsc]

Dear Fellows, Before this i familiar with AB, each timer in AB we can see status for 'Timer done bit' and 'Timer run' eg. T4:0/DN and T4:0/TT. What about S7 is there any status bits for it? I use Ladder regards dsc

[Groo]

With Siemens you have different timers, on delay, off delay, pulse timer, etc and there is only one status bit for each timer. A quick overview, in each case the example presumes Timer 1 used for the timer: On Delay Timer, S_ODT. Timer runs onlywhilst S input is on. After preset time the boolean contact T1 will come on. If the S input goes off, the timer will reset and T1 will go off. Off Delay Timer, S_OFFDT. T1 comes on as soon as the S input comes on and stays on for the preset time after input S goes off. Retentative on delay timer, S_ODTS. As the on delay, except once the S input has come on the R (Reset) must come on to stop the timer and turn T1 off. Pulse timer, S_PULSE. This timer T1 comes on as soon as input S comes on, but goes off after the preset time, even if input S stays on. If input S goes off, T1 goes off straight away. Extended Pulse Timer, S_PEXT. This is like the pulse timer, except once the pulse time has started it will complete, even if S goes off. So no, there is no DN or TT real term equivalents.

[ramaslabas]

I am familiar with Siemens S7 and have some experience with AB. AB has perfect functions for timers as "timer done" or "timer run". In S7 you should make those functions in ladder.

[JesperMP]

Hi dsc. With your background in AB, I recommend that you use the IEC timers and not the S5 timers. The IEC timers resemble the AB timers the most. The S5 timers are very different, and I think they are mostly included for backwards compatibilty with S5. edit: the .Q output from an IEC timer is the same as the DN bit on an AB timer. There is not the same as a TT bit on an AB timer. You may have to derive it. For example TT = enabled AND NOT .Q Edited April 7, 2007 by JesperMP