Variable Timer on FX2n

Hey guys! first off I hope this post is in the right place...?
second, i hope it hasn't been covered before. I did do a good bit of searching for this before I joined and I could not find an answer to this.

essentially i need a timer where the preset time can be adjusted by an operator using a touch screen - is this possible? If so could somebody give me some pointers on it?
just to clarify...a user would enter a time in mins via a touch screen and the timer would then run for this desired time period.

I have some fairly basic working knowledge of using step7 but I am completely new to using GX Developer and im struggling.

Thanks in advance
Damien

Just use a register (i.e. Dxxx) instead of a constant (Kxxx) for the preset. The HMI would then write to this register (scaled accordingly). You will probably want to use a retentive register so it maintains its value through a power cycle.



-Eric

From an FX1N manual:

General timer operation

Timers operate by counting clock pulses (1, 10 and 100 msec). The timer output contact is
activated when the count data reaches the value set by the constant K. The overall duration or
elapsed time, for a timers operation cycle, is calculated by multiplying the present value by the
timer resolution, i.e.

A 10 msec timer with a present value of 567 has actually been operating for:
567 × 10 msec
567 × 0.01 sec = 5.67 seconds

Timers can either be set directly by using the constant K to specify the maximum duration or
indirectly by using the data stored in a data register (ex. D). For the indirect setting, data
registers which are battery backed/ latched are usually used; this ensures no loss of data
during power down situations. If however, the voltage of the battery used to perform the battery
backed service, reduces excessively, timer malfunctions may occur.



-Eric

Hi there, thanks for the reply!
So it is perfectly possible then. i'm guessing that this will be mostly done from the HMI then? I just need to make sure I set the timer up as a register not a constant.

Thanks again for the help

Damein

The HMI will read/write that register, but keep in mind the resolution of the timer. You wrote "a user would enter a time in mins", so the value would have to be scaled to the correct value. For example, a 100ms timer set to '2' would run for 200ms, not 2 minutes. You would need a value of '1200' to get a 2 second timer. Where the scaling is done (HMI or PLC) is up to you.



-Eric

Eric Nelson said:

You would need a value of '1200' to get a 2 second timer.

Click to expand...

The highlighted should have been minute, not second...



-Eric

Thanks for all your help Eric, I'll take a look at this now and see how I get on with it.

Cheers