Problems with module EXF-RC15

[Miguel Rojas Brenes]

Hello.

I have two situations:

 

One:

 

I am working with the Module EXF-RC15, PLC SAMBA and stepper motor.

The communication is ok, but I have a problem in the PTO configuration.

In the PTO Move, when I start the move (MB100 from PLC samba), I get a number one in MI107 STATUS PTO. I saw the information and it said that a number one means "1  -  Configuration data is invalid".

 

I reviewed and followed the example C:Program Files (x86)UnitronicsUnitronics VisiLogic_CExamplesVersion 900Project examplesCommunicationsEXF-RC15, but I don´t find the problem in my program.

Please I need your help.

 

I attach an image and the program of the module EXF-RC15.

 

 

 

 

 

 

Two:

 

I need that the movement of the motor stepper with PTO MOVE to be done every time that an HSC counts 4 pulses from an encoder.

The encoder has 400 ppr and it is in a motor 3 phases ,1800 rpm.

what is the correct process for this application?

do I need an interruption for this application or not?

If I need an interrution, do you have some example?

 

This application is for a transformer rewinder.

 

 

Regards.

 

 

 

 

 

Módulo EXF-RC15 V5.vlp

[Simon]

Hi Miguel,

You are describing an encoder follower.

Firstly, in response to your second question, I think there is a speed and response time problem. Just doing the maths on your encoder signal, with a 400ppr encoder at 1800rpm, you will get at least 12,000 pulses per second.  Depending on how you have set up the high-speed input you could be seeing 2x or 4x that many pulses (24 or 48kHz).  if you want to trigger an event (PTO move) every 4 pulses, then you are trying to trigger an event at least 3000 times a second.  Even with interrupts, the fastest is 1.25ms (800Hz).  The PLC can't respond fast enough.

Do a quick check on your encoder, turn it one revolution and see how many pulses you get.  Often the PPR specification of an encoder is for each single channel.  So a 400ppr encoder gives 800 or 1600 pulses when using the (A,B) Shaft Encoder 2x or 4x settings , or just 400 pulses if you use just a simple High-Speed counter.  

I suggest dividing the encoder pulses by some factor so that you are executing your PTO move less frequently, maybe 10 -100 times per second.  Obviously each PTO move will then need to be more pulses.

That's looking in terms of your second question, from that point of view. 

However, I don't think you will get what you want by attempting to re-trigger multiple PTO moves.  This suggests each move needs to be completed before the next one starts, and that will not give you continuous motion.

I'd suggest that you start the move when the encoder begins to turn and then continuously update the target position based on the pulses received from the encoder.  That is, add pulses to the target position, using your scale factor from input encoder pusles to output stepper pulses, and do this 10-100 times a second.  In this way the move never ends until the input encoder stops rotating.  i think this will work, but I don't have a system to test with right now.

Hope this helps,

Simon

[Miguel Rojas Brenes]

51 minutes ago, Simon said:

Hi Miguel,

You are describing an encoder follower.

Firstly, in response to your second question, I think there is a speed and response time problem. Just doing the maths on your encoder signal, with a 400ppr encoder at 1800rpm, you will get at least 12,000 pulses per second.  Depending on how you have set up the high-speed input you could be seeing 2x or 4x that many pulses (24 or 48kHz).  if you want to trigger an event (PTO move) every 4 pulses, then you are trying to trigger an event at least 3000 times a second.  Even with interrupts, the fastest is 1.25ms (800Hz).  The PLC can't respond fast enough.

Do a quick check on your encoder, turn it one revolution and see how many pulses you get.  Often the PPR specification of an encoder is for each single channel.  So a 400ppr encoder gives 800 or 1600 pulses when using the (A,B) Shaft Encoder 2x or 4x settings , or just 400 pulses if you use just a simple High-Speed counter.  

I suggest dividing the encoder pulses by some factor so that you are executing your PTO move less frequently, maybe 10 -100 times per second.  Obviously each PTO move will then need to be more pulses.

That's looking in terms of your second question, from that point of view. 

However, I don't think you will get what you want by attempting to re-trigger multiple PTO moves.  This suggests each move needs to be completed before the next one starts, and that will not give you continuous motion.

I'd suggest that you start the move when the encoder begins to turn and then continuously update the target position based on the pulses received from the encoder.  That is, add pulses to the target position, using your scale factor from input encoder pusles to output stepper pulses, and do this 10-100 times a second.  In this way the move never ends until the input encoder stops rotating.  i think this will work, but I don't have a system to test with right now.

Hope this helps,

Simon

Thank you for the answer.

could you do a example in visilogic ?.  I don´t understand you idea completely.

Regards.