Speed control with rslogix 500

Hello all! I wrote two weeks ago with a need for direction while trying to write my first analog speed control program. I am using a Micrologix 1200 with a 1762- IF20F2 analog combo mod. I have started a 2nd ladder for scaling my I/O and the 10K POT that I am using for control. The first rung has only the SCP instruction which I wrote as following:
Input I:1.0
Input min 0
Input max 16 that is the max voltage from my POT
Scaled min 0
Scaled max 32768
Output O:1.0
Is this correct? and what writes to this SCP? Does anyone have the time ( and patients ) to help me with this?
Thank you Nick

You are getting close. Reference the following link for the MicroLogix 1200 manual:

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1762-in005_-en-p.pdf

You need to check the configuration of your analog card. Using RSLogix 500, go into the I/O Configuration, highlight analog card, and press Adv Config, then Analog Configuration. You can set input type to voltage or current for each channel.








The scaling for each is 0-32760. So your scaled max should equal 32760.
What is the input voltage of your pot? 16 volts? The analog input can accept 0-10 volts. You should set the input max to the max volts * 3276. For example, if the max volts is 10 then you would enter 32760, this is the limit of the analog input.
What are you driving with the analog output. You will have to know whether it is current or voltage and what range it is looking for.

What is writing to the SCP is your POT through input 1.0.

You need to make sure that your wiring is correct. If you want to control the analog input with a pot, it will need to be wired as a voltage divider. Additionally, the analog voltage input is 0-10Vdc, so if your source voltage is any higher than 10V, you'll have to use appropriate resistors in your voltage divider.

Input I:1.0
Input min 0
Input max 16 that is the max voltage from my POT
Scaled min 0
Scaled max 32768
Output O:1.0

Click to expand...

To determine the input max for your SCP, you need to know the resolution of the analog input card. For the card you have I believe it is 12 bits. So that means that at full voltage (10V) the input max will be 2^12 or 4096.

Also make sure the cards dip switch(es) is set for voltage, the default is current.

thank you, I should let you know that I want the end result to be like this: The POT write to the analog input and the 4-20ma output will go to the Drive input as a 4-20ma signal. Thank you very much for your help so far, I will make the corrections in RSLOGIX so that my card in configured the right way. Can I use the scaling to max (32768) = 20ma?

thank you, I will be re-creating a new power supply so that I dont have to include any resisters, this is my first analog program and I thank you for your response. I will make these changes and let you know how I did. Nick