Error code: -200077

[Dennis_Knutson]

The DAQ Assistant always uses dynamic data. With the lower level DAQmx functions, the data type is a function of the polymorphic type of DAQmx Read, number of channels, etc.

[JohnS11]

Dear dennis,

Thanks for your feedback.

ok. help to check.

what i intend to do as follows. i want to drive the motor follow the setpoint profile using a pid( at time 0s, setpoint is 0; at time 5s, setpoint is 5; at time 5s, setpoint is 5). The ouput from pid will ask the DAQ assitant to generate the voltage which will drive the motor. 

The total distant travel can be calculated using the encoder.

if the (setpoint - total distant travel) < 0    (This means, overshoot is happen)  , motor has to be in the reverse direction (this can be done by ON the two Digital Output line)...

help to critics the vi if you found something wrong there.

if possible, help to correct the vi if you found something wrong there.

[JohnS11]

help to spell out what's wrong in the code if can.

[JohnS11]

the said vi give error -200561

-200561.png

what does it means by DAQmx write <analog 1D DBL N Chan 1 samp) ?? help to share

[Mcdan · Accepted solution]

John,

That error tells me that you attempted to write a value of 199.84 to your analog output channel.  The range of the channel is +/- 10 V.  Since the data exceeds that range, you get the error you see.

Dan

[Mcdan]

Additionally, to answer your question:

what does it means by DAQmx write <analog 1D DBL N Chan 1 samp) ??

DAQmx Write (Analog 1D DBL N Chan 1 Samp) is the version of DAQmx write that was called (this is somewhat hidden from you by the DAQ assistant).  If you use the lower level DAQmx API directly, there are many different version of DAQmx write to choose from, and you'd pick based on how many channels are in your task, the format of your data, etc.

Hope that helps,

Dan

[JohnS11]

thanks for the explanation....how to improve the vi?

[JohnS11]

Dan,

I failed to find out the following:

What's the right way to define the sinusoid movement (forward for a meters distance and reverse for a meter distance) in the setpoint pid?? help to share..thanks.

[Mcdan]

John,

I'm the first to admit that I haven't done much with PID control before, so maybe someone with more experience can speak up.  Is it valid to turn on relays to reverse the motor direction via relay when you see overshoot?  I would think that the PID algorithm itself should account for overshoot.  By turning on relays and reversing the motor, are you not going to get a non-proportional response?

What is the relationship between your analog output (voltage) and the response of your motor?

Dan

[JohnS11]

analog output will generate the pwm to feed in motor