valsidal.alu

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william: I do not know the reason why this can not be done synchronization. there S7-1200 and used for measuring the length of the IRC. SIMATIC but still can not :-( I think it would SIMATIC convert frequency to voltage mastered. How much of a difference in the Logo programming and Simatic?

 Hi.

There is big differences between the S7 range and the LOGO. The LOGO is "under powered" to not compete into the S7 market. LOGO is sold as "intelligent relay".

Simple examples for S7-1200 -
S7-1200 can read 100kHz (special) inputs. With small program the PLC cycle is less than 1ms - normal inputs can be read at 1kHz. Pulses can be generated at 100kHz with open loop motion control adjusting frequency for ramp up, run and ramp down to a target.

What is "measuring the length of the IRC"? Measuring length and synchronising speeds of drives are not the same. Especially if speed is not controlled directly.

Maybe what I understand about what you need it wrong. Maybe you need to measure distance and not synchronise speeds. I am human - I am regularly wrong. Help me (us) help you.

Please..
* Make a picture explaining what you need to do.
   Hand sketch is okay.
   Where is tube and where is blade + what to synchronise.

* Does the tube speed stay constant?

* How accurate is cut needed?

Regards.
w

I need to synchronize the speed of the truck saw with speed tubes.

cutting accuracy +/- 2 mm to 4 m at a speed of 25 m / min.

valsidal.alu

I need to synchronize the speed of the truck saw with speed tubes.

cutting accuracy +/- 2 mm to 4 m at a speed of 25 m / min.

Hi.

Please be patient with me a little longer.

Thank you for the image. This is the picture I had in my mind from your description. There is however something missing.

Could you show us the movements of the saw - please. We need to know what movements are synchronised. In my mind I see a "flying saw" application.

"Flying saw" is where..
The saw blade moves in synch with the pipe while moving down to cut. With the saw blade still moving in synch, the saw blade moves up. There after the saw blade reverse back to the origin.

Please confirm if my thoughts are correct.
w 

valsidal.alu

Here is the "gross" drawing saw.

Thank you for the image.

I will try to explain the difficulties of this application...

Let us assume for the moment..
  The LOGO calculates the analog output
   and the exact sync speed is achieved for the saw blade movement.

When should the LOGO start the movement to ensure the right cutting position? Remember that the saw blade takes time to move from standstill to the sync speed. The sync speed differs so the position where the saw blade starts moving differs. How will the LOGO calculate this?

What happens when the pipe speed changes while a movement has started or is already cutting? How quick should the movement of the cutting blade change?

For "flying saw" applications we use servo driven systems... I think that a "flying saw" is what you are describing as your application.

w

Hello Valsidal,

If you really don´t want to buy a F/V converter and you have a Eletronic Lab., you can use a LM 2907 or LM 2917. See data sheet.

I can send you a circuit.

Regards,