servo loop without new daq equipment

[tavwtby]

Hello all, I have a test rig that applies a load dynamically at apporx 5 hz. This test rig never worked correctly. What I am trying to accomplish is to control the servo which is +/- 5vdc to apply the load on the cylinder which has a load cell for feedback. Also, I will need to correctly lag the frequency so it is reversing in unison with an rvdt signal. In other words, the sine waves will either be on top of one another or 90 degrees phase lag. There is no money for this rig to buy anymore daq devices, so I have to make it work as is. I am using a cRio 9014with analog in, analog out, and digital out to control the servo. My trouble is I am stumbling on the code to control the servo so that it reverses load. Any help would be greatly appreciated. Thanks

[Ben-N]

Hi tavwtby,

I'm not totally sure I understand your question.  It sounds like you are trying to use a 9014 with some DO lines to control a servo drive, is this right?  It sounds like the servo you are working is expecting a sine wave to communicate, is this right?  Depending on the phase shift, the drive will respond differently, is this correct?  I'm not sure I have a good grasp on the big picture of what you are trying to do, can you give us a more complete picture on what is happening?

You also mentioned that the test rig never worked correctly.  What do you mean by this?  Was the control system not working at all, or not as you expected?  Is your servo expecting a DC voltage from your analog out module that is then being converted into a sine wave on the drive, or is your servo just responding to a +-5 volt signal from the analog out?  We are going to need some more details to get you pointed in the right direction.