Counter range(Step7)

Hello all.

I have a problem with the counter range in step 7. The maximum range is around 32768 i think and than it jumps to -32768. The thing is that I have a encoder wich gives me 128 impulses per turn. 1 turn is therefore about 0.5 meters in distance. My counter must go at least 4.0 km in distance. So I would have to at least duble the range of the counter... How could I do this???
Any ideas???

Thank you
>Ales<

I would suggest you face this from the software point of view which will enable you to have complete control of the devices. We often use this sort of philosophy for both absolute and relative encoders in order to reset and control them "process-wise" instead then leaving it ot the devices themself..

Mandi
Simone

I'm kind of unclear what you are talking about. S7 counters have a limit of 999 (which makes them kind of useless in general). Are you talking about a specific counter card? If so, all of the counter cards I have used have a 32bit range, which is much more than you would need. Give us some more info, and we'll help you out.

Hello NoName,

Could you reset this type of counter at each revolution and count up the revolutions as rough tracking and use the impulse counts as finer tracking?

NoName,

What I use for increasing timers & counters is to have the tim/count-er count to 30,000 (/100 seconds if timer) then add 1 to a second counter & reset the first.

Then your second counter will be 1 for every 5 minutes of time, or if using pulses change the 30,000 to whatever count you get every inch or centimeter.

Reset both accumulators at start of cycle for accurate measurment.

I am not sure what the resolution you require for this application. Have you considered using the marker pulse (1 pulse per revolution). If 1 revolution is .5M then 4 km wouldbe 8000 pulses

Why doesn't anyone listen?

What I use for increasing timers & counters is to have the tim/count-er count to 30,000 (/100 seconds if timer) then add 1 to a second counter & reset the first.

Click to expand...

Doesn't any one see what is wrong with this plan? Never reset the encoder because you loose a fraction of a count each time your reset!!!! Over 4 km this could result in significant error.

See the last post

The marker pulse is only required when homing the system.

Finally. I hope this system that must go 4 km doesn't slide or slip.
Othewise you will need to 'home' in many places.

Thank you all for your reply's.

As for what type of counter I am useing. I used the add_int function, not an ordinaray step7 counter. And just add 1 for every impulse that the encoder gives me.
The measurment must be +-10cm accurate.
So I can't reset the counter when it reaches 128 impulses and increment another counter by 1 at the same time. I loose about 2 cm each turn(revolution9) this way. Have tryed it over and over again and couldn't get it to work properly.

About the sliping and slideing... Peter. I hope that it will be minimum, but you never know until you test it. I start on site testing next weak, so I'll be able to tell more about this if it occurs later next weak.

Right now I'm playing aroung with the floating poitn math instructions... got the idea form your link Peter.
Thank you all for your contribution so far.
Regards
>Ales<

If you are manually adding 1 to an integer register, the answer is simplicity itself.

Use a DINT.