lvb

One of my favorite keyboard shortcuts in MS Office is the "F4" key. I can't even begin to explain how much time it saves me in word when I can highlight a table, change the ENTIRE formatting and then just click on each remaining table in the document and press F4 to magically make all of the table formats the same. This is due to the "Repeat previous action" or "repeat last command" option in MS office. Please tell me this option is available in LabVIEW!

I am currently in the process of replacing a specific VI with another. I wrote some simulation VI's and would like to quickly replace every instance with another VI when simulating and then vice versa when running with real hardware. Please tell me there is some way to do this other than manually!

:headbang:

Help!

Wow, thanks for the quick responses. To start out, this is a practical application in which I need to acquire and plot torque vs time and torque vs position (or encoder ticks) for a motor moving an object. The average time to capture data will be anywhere from 1-30 seconds. To get more specific what I am looking for and answer some follow-up questions:

I would recommend using the encoder input as your sample clock for the AI.

So for each encoder pulse, you get an analog reading.

Go to the Help->Find Example and search for "sample" or "sampling". Poke around there for some examples of how to configure the sample clock.

-James

I took a look at: Ack&Graph Voltage-Ext Clk.vi and Cont Ack&Graph Voltage-Ext Clk.vi. However, there are two problems I may encounter with this approach:

1. I may need multiple samples between encoder ticks

1. I need to have the ability to display time on the x-axis

What exactly are you measuring and what sort of decision do you need to make based on the data?

This is very important to give you a useful answer, and I am not fond of spending time explaining the wrong solution.

This should be answered above

You need to decide what the encoder is for. Is it a rotary encoder? Are you intending to measure voltage as the encoder rotates?

Is the encoder a linear encoder? What is the encoder resolution?

Do you need to calculate very fine average speed between encoder ticks?

Do you really want your data taken in the time domain? In other words clocked by the daq card clock

Or is what you really want the voltage at a particular rotational position or at a linear position (depending on the encoder), the angle or length domains?

Speed is not calculated, just torque vs ticks displayed.

The user needs to be able to select torque or time from an x-axis listbox. This will update the display of the acquired data plot.

I did a bit of searching on counter/timers and encoders on the NI website and in Find Examples, but did not find much regarding plotting analog data vs encoder counts.

Does anyone have advice on the best method of achieving a plot of x-axis (encoder counts or pos.) vs y-axis (analog input)? The best method I can think of is:

• creating a 2D array that stores the timestamp of the analog sample and voltage
  
• creating a 1D array of encoder tick timestamps
  
• graphing timestamp vs voltage
  

This is all theory, but not implementation. Please advise...

Thanks!

Is there a reason you don't want to use the PID toolkit? You caould always code up a PID model yourself, but it'd take you more thime that the toolkit's worth...

Management...

I was wondering if anyone here could share some advice about closed loop control with or without the NI PID Toolkit in LabVIEW.

I have an analog output replacing a potentiometer on a current control module. Previously the current draw potentiometer was set on the current control module to a value between 0-100 (reading on front of pot).

If the operator set the value to "50"... as temperature and other factors changed, the machine would drift and the current draw setting on the pot (0-100 range) would no longer be valid.

I would like to control an analog output (0-10V) to maintain a constant current draw in the system. The feedback is from an analog input via a torque sensor. The frequency of the control is on a cycle basis (once a minute). Any advice?

Thanks!

This could be a little tricky because the enum control doesn't have an equivalent selector object. It only has an increment decrement. The selector equivalent is the entire text field. Pasting a down arrow there will replace the text field and is messy.

I would suggest, instead to decouple the GUI requirements from the diagram data requirements as indicated in the image. This way you can use whatever you like as a control and still get the benefits of enum datatypes on the diagram.

Excellent! This actually solves a readability issue with all of the LabVIEW programs that I have inherited. Now I can go through all of the case structures and replace mystery numbers with descriptive text. Thank you for the great tip!

I would like to create a control that has Enum data type, but looks like this (menu ring):

The Enum does not have a drop-down arrow for the user to realize more options are available, and I find the Menu Ring control more clear.

Is this possible?

Thanks!

I took a look at NI's Test Stand, but it seems to be more complex than I want the technicians to deal with. Any chance you could post/e-mail some of your block diagrams for reference? I am looking to do the exact same type of application.

Any one else have some examples of such an application?

Thanks!

I am fairly new to LabVIEW (6 months) and looking for a solution for test and measurement. There are a few types of tests that we run: state machines (wait for a certain set of digital inputs), ramping tests (increase output until certain input is hit), and position/voltage control (maintain a position/load/acceleration) and also log test data to a database. I would like to create an environment where a user could “program” a test with ease. We currently have the capability of a state machine with digital inputs, but lack the ramping and position/voltage control. I was wondering if the community here could recommend some examples/solutions for this type of application. Also, I was wondering if anyone has examples/resources that allow a user that has no LabVIEW experience to “program” this type of machine. Basically to create an environment where the user could select certain steps in a sequence and have that sequence repeat, for example:

Step 1. Output the voltage on channel "n" to 10.0 V

Step 2. Wait for digital input "x" to turn on

Step 3. Increase the voltage on channel "n" at "y" Volts/Sec

Warning: this is also cross-posted in the official ni forums, but I figured I should try to get feedback from both communities. Please respond with your advice!

Thanks,

Brian