Recieved via PM

from Stylingalong

Gentlemen (includes ladies);
I am looking for some help on my latest project. I want to use an encoder to get position and the use the PLS function to make certain actions happen from that position. I am reading all the stuff that I can get. I currently use AB845H Encoders, but have access to others. O.K. Now to thereal question. I am not running at high speed and only require a minimal accuracy of around 1 degree. What should I use for an encoder?
Second pleading. Does anyone have a small program that I could look at for guidance. I am vary familiar with progromming on the SLC platform (no HSC or encoders).
Any help will be greatly appreciated.

PLEASE POST THESE KIND OF QUESTIONS IN THE GENERAL FORUM
You are only limiting your chances at getting help.
I have never used the ML1200 encoding.

I'm new at this, but I will try to post elsewhere. Thanks for your help

Right here is fine. You will find lots of people willing to help.

Stylingalong-
The type of encoder you use is mostly determined by your required resolution and the electrical specifications of whatever the encoder goes into. You have listed your resolution already as 1 degree. So anything with greater than 360 PPR will work for you. Actually, if you use quadrature decoding on an A-quad-B encoder you could get by with anything greater than 90 PPR.
Your encoder count will also be determined by the highest frequency you can deal with, both on the encoder side and on the input side. You say you are 'not running at high speed'. That's a bit open ended to determine a spec off of. But as a basic criterion you need to make sure your pulse frequency is below the max frequency of the encoder and the reading device.
Can you live with referencing the encoder? If you use an incremental encoder you will need to reference your axis at power-up. You could use an absolute encoder but that would require many more data lines. You would need 9 lines minimum to get 1 degree resolution. If you can live with referencing stick with the incremental encoder. It's alot easier to deal with from an interface standpoint.
As for encoders, the AB line is pretty pricey. But they are pretty bulletproof, too. If you have one already just stick with it unless you need to change resolution of interface. Automation Direct sells some cheap encoders and they stock most of what they sell. Encoder Products Corp. also has some pretty cost-effective offerings. A good middle-of-th-road encoder cost-wise is Stegmann.
Please come back with any specific questions you have and we will see if we can help.

Keith

O.K.
Here are some more details for you to work around. The output shaft that I will attach to will rotate at 80 rpm max. AB 845H is an incremantal encoder that I could attach to input 0 (or 1) of my Micro 1200. The HSC will count each pulse? The PLS function will then allow me to set gates for lets say a solenoid to come on/off. I have not done this yet so I am still doing some assuming.
Now my problem is that I need to know where the "0" position of the machine is.
If I go back to an absolute encoder I will defeat the purpose of the HSC in the MicroLogix 1200. It sounds like I may need to go back to using an Omron PLS 24 gate relay and send the digital input separately to the PLC to deal with on an individual basis.
OR:
Could you suggest a method for doing a zero routine in the 1200 PLC? The way I am reading the HSC instruction appears that it is possible to send a signal (maybe the Z pulse) as the zeroing influence and therefore still be using an incremntal to do the counting. Any help is good. Thanks

Use separed sensor for HOME point and in that point reset the HSC.
If your cycle is one round of the encoder you can use that as zero point and reset the HSC.
The HSC will count each pulse.and you can do any operation you want
on that word.

Arikby;
That is a very helpful suggestion thanks.
Your English is very good.