how to replace the system clock memory bits by self-programming?

Hello,guys,

How to replace the system clock memory bits by self-programming programs for porting to other platforms?

thank you very much.

Hi 5Zkgkdr,

WR_SYS_T: Set time-of-day

unknown user

Hi,bro!

I want to know how to creat the pulsing bits to replace the system clock memory bits, can you help me?

Thanks a lot.

the easiest and most bombproof way to do it (in my opinion) is set up a cyclic interrupt (OB3*) at you total cycle time, this will be 1/Hz if you like thinking in frequency.

In the OB3* you simply set your a global bool tag to true.

AT THE END of your main program you set this global tag to false.

This way you will have a tag that stays true for one program cycle every x us.

If you want the pulse at 50% duty cycle like the clock signal you can add in main a timer_tp(in:=yourPulse, pt:= yourCycleTime / 2). at this point the output timer_tp.Q will be your clock.

If you try to do this with 2 timers be careful, they will get stuck after a CPU stop/start unless you create the initial rising edges.

Hi

You can use tick count )S7-1500 has such variable or in S7-1200 have timer with max time set and output to reset)

latch tick count

and if current tick > last tick time = (current-last)/1000 [s]

otherwise it is an overflow and you do a trick

time_diff = (max-current_tick) + previous_tick+1

Thanks for your answer,maybe I had not described my question clearly.

What I mean is that how to program my own pulses programs to replace all the pulse bits,such as always_on,always_off,clock_1Hz,clock_0.5Hz and so on,so...

Finally， I sincerely thanks for your help again.