rotating actuator lead screw

[labview1958]

I am rotating an actuator lead screw using labVIEW 6.0. My code works. It is attached. However the specs for the actuator says that one FULL turn consists of 48 steps. But to rotate my actuator lead screw using labVIEW 6.0, I need 192 iterations for the FOR LOOP. I thought that it should be 48 iterations. Why? Anyway 4x48 gives 192. Is there a connection?

[AnalogKid2DigitalMan]

LV1958

We need more inofrmation on your hardware, like make/model of motor and screw. From your code it looks like you are toggling a bit on the digital port to send a pulse to a motor driver. Could it be that the motor driver has a microstepping mode where 1 pulse only provide 1/4 of a step of movement???

By the way, there is no data flow with regards as to when the 50msec delay occurs before or after setting the bit state. So you could get 0, 50, or 100msec delay between bit toggles. I suggest you rectify that situation, or use a counter output on your DAQ card as opposed to a digital output if your hardware has that feature.

[labview1958]

I am using 6025E DAQ card connected to a RS217-3611 driveboard which is in turn connected to a L92411-P2 digital linear. It states 0.0254 mm linear travel per step. It does not mention how many steps per rotary turn. I guess it is 48.

[labview1958]

Actually I e-mail the manufacturer who replied that the actuator can move 48 full steps in one complete turn. Does the digital port.vi gives out a signal 8 times for each frame?

[labview1958]

I understand that the actuator has 48 ferrite poles composed of 4 coils. Is that possible that I get 192 iterations from 48x4 = 192?

[AnalogKid2DigitalMan]

Can you direct me with links to the web sites for the data sheets for the driver and motor, I am having trouble finding them.

[Ray.R]

It appears that way...

More fine control, maybe?

[labview1958]

The driveboard specs can be foun d at http://rswww.com and the digital linear actuator at www.mclennan.co.uk. I hope someone can explain.

[AnalogKid2DigitalMan]

LV1958:

I am at a loss here. Typically a step motor rotates so many degrees/step. It appears the motor on the linear actuator is 7.5 degrees/step based off of 48steps/rev factor you state. 7.5 degress is common for step motors. I cant say why you are a factor of 4 off. When you give the driver one pulse, it should move the motor 1 step unless the driver is in half or micro step mode. I see your driver does support half step mode, make sure that you are not in this mode which could account for 1/2 of your 'error'.

Ignoring rotary motion, what about linear motion? The lead on the motor screw is 0.001"/step. I would suggest you set your loop to 1000 iterations and see how far it travels. If all is correct, it shoud move 1 inch (1000*0.001).

Hope this gives you some 'leads' to go off of.

Again, please take note about my previous comment about data flow and timing delay uncertanty in your code. This could potentially be a source of error. You could always use 4 sequence frames total, 1st for digital bit firing, 2nd for delay, 3rd for digital bit firing, and 4th for delay.

[labview1958]

I thought 1 iteration means 1 FULL step. Then I checked that I have TWO sequence frames. Does that mean 1 iteration is two FULL steps. I have already checked the connections. However I am away from the lab so I cannot test for a while. As I recalled one FULL step actually consists of 4 sequence like, 0011, 1001, 1100 and 0110. So 48x4=192. Any logic here? Another possiblity is that it has 192 poles. I wants recieve an e-mail answer from mcllenan.uk that the actuator has 48 ferrite poles.