HSC Encoder Zeroing with Sync input

qwazee

Hello.

The best engineering solution is using an absolute encoder. What you are doing now has risk, especially if you do not have a sensor confirming a position.

Your description of the 10 turns do not yet make sense to me. Allow me to pause at the quoted points.

Yes your right its risk and not a good engineering but it was building with this way for years, there is no voluntariness about the change that :/

10 turns or 100 turns no difference it must end up with same position as angle . For example my axis start  operating from position 30° after 10 exact turns,; final angle : 30°

qwazeet

Requesting a movement of -720° is okay. The minus indicate the direction. The position is the problem. Starting at 20° moving -720° should end up at 20°. If you make it -20°, all hell breaks loose.

 it has to be end up with +20. Other way it will be wrong defination of position.

unknown user

What happens now if you move +360°? Do you end up at -20° or +20°?

This is a vital piece.

 if axis at position +20 after one turn on clockwise it should be again at +20°

yes it seems complicated, may be I should use only 0-360. Minus angle just for exhibition on the HMI screen, I can show it according to position and direction of movement.

{ moved to attachment }

qwazee

<snip>

1. A dual phase encoder is essential. I would strongly suggest the use of quadrature pulse, which means you will have x4 pulses that of your encoder specification. Encoder rated as 2000ppr will give have 8000 pulses counted by the PLC.
   
   
2. On startup you mark a bit that blocks movement until the user manually moved the rotary axis in position.
   
   
3. The user moves the system to a position. It is best if it is a fixed position. This could be two markings, one at a fixed position and one on the rotary part.
   
   
4. The user confirms that the manual correction is done. Continue to the next step if the position is fixed. Else the user should say which position is used as a reference.
   
   
5. The current encoder count is captured {#dintEncBias}, as well as the position {#realDegBias}. The position could be fixed or user defined. This is the reference point for all future positions. It is legal for as long as the PLC is powered or until the user reference the position again.

</snip>

Why are you changing the controller, could it be that it never worked well and they were not happy with it?

Back to how it works:

How is it comanded, do set a position, run the machine and it should stop there?If yes, is the position in whole numbers? Like a carousel with bottolles and you position the bottles under a tap.

Or, do you run it forward and back to any position and want to know where start and end are? Imagine a cable winch where you roll it up and down to any height arbitrarily and still want it to stop by itself at the fully coiled or fully uncoiled points.

Sorry Ibrahim, I have made some change in the code. It is attached as a text file in the previous reply.

Kal.A and I agree. There should not be a reason to change the PLC to firmware V4 with the system description  you have given us now.

Good luck.

Kal.A

Why are you changing the controller, could it be that it never worked well and they were not happy with it?

Back to how it works:

How is it comanded, do set a position, run the machine and it should stop there?If yes, is the position in whole numbers? Like a carousel with bottolles and you position the bottles under a tap.

Or, do you run it forward and back to any position and want to know where start and end are? Imagine a cable winch where you roll it up and down to any height arbitrarily and still want it to stop by itself at the fully coiled or fully uncoiled points.

 I changed controller because of input filter time of the PLC for Digital inputs, it was to long.

For this axis thing about a drum like in a washing machine, It can turn one direction continously for a while or It can move clockwise and counter clockwise respectively with an setted angle like; first  +90°, then -90° for a while. The important point is zero point, axis starts job and finishes its job at 0° otherwise it can cause mechanical problem.

 Hello.

ibrahim454

Thanks for code, 
can you clarify these two value ;

The current encoder count is captured {#dintEncBias}, when captured? captured by Z pulse ?
and position {#realDegBias}: is this reference point?

Earlier was stated:

qwazee

<snip>
You do not need the Z-axis for the following concept.
You should not allow the HSC to be zeroed by any outside signal.
The count of the HSC is left as is.
</snip>

qwazee

<snip>

1. On startup you mark a bit that blocks movement until the user manually moved the rotary axis in position.
   
   
2. The user moves the system to a position. It is best if it is a fixed position. This could be two markings, one at a fixed position and one on the rotary part.
   
   
3. The user confirms that the manual correction is done. Continue to the next step if the position is fixed. Else the user should say which position is used as a reference.
   
   
4. The current encoder count is captured {#dintEncBias}, as well as the position {#realDegBias}. The position could be fixed or user defined. This is the reference point for all future positions. It is legal for as long as the PLC is powered or until the user reference the position again.

</snip>

In other words (operational procedure):
a) Power on

b) User activate manual mode

c) User jogs movement to a position

d) User tells the machine the degree position
     Position is saved  ........................... realDegBias

e) PLC program reads the position of the encoder
      Position is saved........................... dintEncBias

f) The two saved positions are used for as long as the PLC is powered

g) The HSC is never zeroed by the PLC program

Good luck