Need help updating using ML1500, HSC, and Encoder

[loundeb2]

Hi Again,
I have a pool wall line that I would like to update. It consists of a payout reel, corrugator, 2 punch presses, a shear, and a take-up reel. The line originally had a 1000ppr line driven encoder on the corrugator which was connected by chain and sprockets. It has a micrologix 1500 using HSC function file with 79 in an integer file moved to the HSC.ACC for pulse per inch conversion.
The line ran ok, but we changed the corrugator and now the same 1000ppr encoder is directly face mounted to the end of the corrugator shaft roller(1:1). The corrugator moves 46.5" of material per revolution, so 1000 pulses = 46.5" or 21.505 pulses per inch.
The lengths we run vary from 500" to 1200" and are allowed a max. 1" variance.
I need to know the best way to improve the accuracy for these long lengths and how can I use floating values for the pulse per inch conversion?
The program is attached. I didn't create this program. I would have allowed lengths to be entered instead of a value for every length with a corresponding calibration file.

Thanks,
Lou

 

[loundeb2]

This is the current program, but it doesn't have the descriptions.

 

[IPSI John]

If I understand you correctly, mechanical modifications have changed your position feedback from 79 pulses per inch to 21.505 pulses per inch. Since your presets are all double-integers (they won’t take floats), you went from +-0.006" to +-0.023" potential rounding error from float to double-integer in your presets, but this is ok since you can have a 1" error. If the +-0.023” error is unacceptable, you need a higher ppr encoder.

I believe you just need to change your presets in your L9 file. For example, L9:1 = 97697 counts / 79 counts per inch = 1236.67". With your new mechanics L9:1 = 1236.67" * 21.505 counts per inch = 26595 counts. You don’t lose much in the rounding.

You can change each L9 value manually, or create a L10 file length 256, copy the current values of L9 to L10 via 4 temporary COP instructions, then create an indexing counter from 0 to 255, multiply each L10:[C5:2.ACC] by .2722 and put the results in L9:[C5:2.ACC], then delete L10 and the temporary logic.

I hope this is helpful.

 

[loundeb2]

Thanks John,
I was afraid I'd have to that.