Experimental Physics and
Industrial Control System

There is an exception in the special case BACC = ACCL, BVEL = VELO.  In this case, a move in the "preferred" direction is done without stopping at TARGET-BDST, because there's no need to switch from normal to backlash speed and direction.
Tim

----- Original Message -----
From: "Kurt Goetze" <[email protected]>
To: "Márcio Paduan Donadio" <[email protected]>
Cc: [email protected]
Sent: Thursday, August 23, 2012 4:52:20 PM
Subject: Re: Motor Record 6-5-2 backlash issue?

Hi Márcio, 

That is the correct behavior. Backlash is two moves, in either direction. 

In one direction the target is /approached/ in a second move by the distance 
set in BDST. In the other direction, the target position is "overshot" by BDST, 
and then moved back to the target. In either direction the second move is 
done with BACC and BVEL. The idea is you can change BACC and BVEL 
for this second move to be less than ACCL and VELO, thus keeping the 
drive screw in contact with the stage, in a controlled way to maintain position. 

In the first case you cite, your positive movement /looks/ to have no backlash 
because BACC=ACCL and BVEL=VELO, making the two moves look to be one. 

HTH, 
Kurt 

On 8/23/2012 4:25 PM, Márcio Paduan Donadio wrote: 



Hi folks. 

When BACC = ACCL and BVEL = VELO and BDST > 0, I see the movement as I expect: for positive movements, no backlash correction; for negative movements a backlash correction. 

But when BACC != ACCL or BVEL != VELO and BDST > 0, something different happens: for positive movements the motor stops before the target and moves again by BDST to hit the target. 

Is this the correct behavior? 

Thanks, 

Márcio Paduan Donadio 
Engenheiro de Computação - Software de Operação das Linhas de Luz 
Laboratório Nacional de Luz Síncrotron – (LNLS) 
Centro Nacional de Pesquisa em Energia e Materiais (CNPEM) 
+ 55 (19) 3512-3520 - [email protected] 
www.lnls.br 

-- 
Tim Mooney ([email protected]) (630)252-5417
Software Services Group (www.aps.anl.gov)
Advanced Photon Source, Argonne National Lab

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Re: Motor Record 6-5-2 backlash issue? Kurt Goetze

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