difference between S7-300 and S7-200 timer

By searching informations abut timer I found some documentation about S7-200 timer. I've read that with retentive On Delay Timer (TONR) in s7-200 current value is maintained when the input is off. I found this also "You can use TONR timer to accumulate time for multiple periods of the input ON"

This is similar behavior that AB retentive timer has.
But unfortunately this is not the case for S7-300 plcs.
If I use Retentive On-Delay S5 Timer I get following behavior:
when input goes from 1 to 0 timer continue to couns time. But I need timer which will work for say 10 sec. But if stop button is pressed current value will be maintained and next time start is pressed timer wiill count remaining time.

How can I acomplished this in Step7?

Thank you for your help.

Pandiani,

dchartier answered your qustion in the first post where you asked the same question: HERE !

Uh, I'm sorry, I missed that . It won't happen again

Helllo Pandiani (and Jesper!);

Just a little note:
Actually, the S7-200 family of CPUs was designed by enginners that had developped the TI505 PLCs (when Siemens bought that division). so many of the functions of TI CPUs are available on the S7-200.
That might explain why the TONR, avalable on the S7-200, is included in the TI-S7 conversion library. Take the time to look at the blocks available there. Those of us who liked working with the TI PLCs can still find some of those blocks useful (although i will not m,ake the mistake of declaring the S7 superior to the TI; different yes, and powerful, but not comparable).
Hope this helps,
Daniel chartier

I manage to do something according to help I've read. As I understood L#1000 means 1000 ms or 1 sec, but what is MD100? I assume it is merker memory but I'm not sure
When I want to see how regular timer works I simply add timer in PLCSIM ( for example T1). How to add this retentive timer FC80? I'm beginer and never had opportunity to work with this stuff so bear with me.
On the other hand I need this because I'm writing simple program for washing machine. I have one pumpe that needs to pump water for say 20 sec. If machine is stopped in the midle of washing process it would be normal to continue from that spot next time it's started. How would you solve this?

The "MD100" mentioned in the help text for "TONR" is the datavariable that holds the elapsed time (ET pin). "M" means that it is in Merker memory. "D" means that the size is a Doubleword (4 bytes !).

In the example the "L#1000" on the PV pin corresponds to a fixed time of 1000 msec for the setpoint.
If you want the setpoint to be adjustable, then you should assign another datavariable on the PV pin, MD104 for example. You can then fill MD104 with a setpoint value from some outher source (examples: a combination of switches, a potentiometer, an operator panel).

Ok, thanks for reply, I understand now.

Regarding my last question, if you need to program washing machine which works for about 20-30 sec and stoping machine is relative rarely, maybe standard siemens timers are not bad soulution. What would you do in my place? Would you use FC80 or not?

I think that if a proces or machine was stopped in the middle of its sequence, then it must be considered an anomaly that should be taken specifically care of.

You can make a memory of which step your washing machine was in, and if the PLC is powered up with a step that does not mean "stopped" then you could prompt the user to "continue the sequence" or to "empty the washing mashine and stop".
If he chooses "continue the sequence" then it could be a good idea to use the FC80 to continue with only the rest of the washing time.
If this is too complicated, then you could also just start the washing time from the beginning.

Yes, at my current knowledge level I'll choose to start from the begining. These processes aren't real , I imgine them and then trz to write programs in order to learn PLC programming.

Thank you for the help.