closed loop control (please help, its urgent)

[st_syd]

Hi,

I have a motion controller (MCCQB from National Aperture) connected to the PC in RS232 (serial). I am trying to control two actuators in parallel. We have an LVDT which provides position feedback, through an NI DAQ board. I have a made a program which works fine in open loop but not in closed loop.

Could you please take a look at the program and tell me if i am missing someting or, if my feedback done wrong. My current program does not seem to be working in closed loop.

I have attached both the open and closed loop programs.

Thankyou so much,

 st_syd

[DjDaveNI]

Hello st syd,

Which NI DAQ card are you using in your setup? The general DAQ cards are highly unsuitable for feedback since most cards cannot do hardware timed single point. National Instruments makes many motion control cards which are designed to handle feedback. Please consider using a card suited for motion control. This explains why closed loop does not work in your current hardware setup.

I hope this helps 🙂

[st_syd]

I am using a NI PCI 6014 DAQ card.
Is this capable of providing DAQ to do closed loop control, or is there some way of making it do so (software wise)?

Other than the DAQ card, is the program which i have made correct?

Thankyou,

st_syd

[DjDaveNI]

Hello st syd,

The PCI-6014 is a B-series DAQ device, and falls
within the category of general non-motion control cards. This card is
not recommended for motion control, because it is not capable of
hardware timed single point (a requirement for reliable feedback). You
must use an NI-Motion card.

As
for your open loop program: if you are able to send commands to the
motor through VISA (RS-232) successfully you should be all set to
operate the motor with no feedback.  Of course, this is not recommended
as you have no way to measure the encoder position point-by-point.

You should also consider using motion control software with the PID toolkit. This software, when used with a motion control card, will permit proper motion control for your application.