tutorial.lyx

CNC 的开放码,EMC2 V2.2.8版

\end_inset 

scope probes
\begin_inset Quotes erd
\end_inset 


\layout Standard

At this point, Halscope is ready to use.
 We have already selected a sample rate and record length, so the next step
 is to decide what to look at.
 This is equivalent to hooking 
\begin_inset Quotes eld
\end_inset 

virtual scope probes
\begin_inset Quotes erd
\end_inset 

 to the HAL.
 Halscope has 16 channels, but the number you can use at any one time depends
 on the record length - more channels means shorter records, since the memory
 available for the record is fixed at approximately 16,000 samples.
\layout Standard

The channel buttons run across the bottom of the halscope screen.
 Click button 
\begin_inset Quotes eld
\end_inset 

1
\begin_inset Quotes erd
\end_inset 

, and you will see the 
\begin_inset Quotes eld
\end_inset 

Select Channel Source
\begin_inset Quotes erd
\end_inset 

 dialog, figure 
\begin_inset LatexCommand \ref{fig:Halscope-demo-3}

\end_inset 

.
 This dialog is very similar to the one used by Halmeter.
 We would like to look at the signals we defined earlier, so we click on
 the 
\begin_inset Quotes eld
\end_inset 

Signals
\begin_inset Quotes erd
\end_inset 

 tab, and the dialog displays all of the signals in the HAL (only two for
 this example).
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-3.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-3}

\end_inset 

Select Channel Source dialog
\end_inset 


\layout Standard

To choose a signal, just click on it.
 In this case, we want to use channel 1 to display the signal 
\begin_inset Quotes eld
\end_inset 

X_vel
\begin_inset Quotes erd
\end_inset 

.
 When we click on 
\begin_inset Quotes eld
\end_inset 

X_vel
\begin_inset Quotes erd
\end_inset 

, the dialog closes and the channel is now selected.
 The channel 1 button is pressed in, and channel number 1 and the name 
\begin_inset Quotes eld
\end_inset 

X_vel
\begin_inset Quotes erd
\end_inset 

 appear below the row of buttons.
 That display always indicates the selected channel - you can have many
 channels on the screen, but the selected one is highlighted, and the various
 controls like vertical position and scale always work on the selected one.
 To add a signal to channel 2, click the 
\begin_inset Quotes eld
\end_inset 

2
\begin_inset Quotes erd
\end_inset 

 button.
 When the dialog pops up, click the 
\begin_inset Quotes eld
\end_inset 

Signals
\begin_inset Quotes erd
\end_inset 

 tab, then click on 
\begin_inset Quotes eld
\end_inset 

Y_vel
\begin_inset Quotes erd
\end_inset 

.
 
\layout Standard

We also want to look at the square and triangle wave outputs.
 There are no signals connected to those pins, so we use the 
\begin_inset Quotes eld
\end_inset 

Pins
\begin_inset Quotes erd
\end_inset 

 tab instead.
 For channel 3, select 
\begin_inset Quotes eld
\end_inset 

siggen.0.triangle
\begin_inset Quotes erd
\end_inset 

 and for channel 4, select 
\begin_inset Quotes eld
\end_inset 

siggen.0.square
\begin_inset Quotes erd
\end_inset 

.
\begin_inset Note
collapsed true

\layout Standard

The siggen component now uses 0 as the starting number, so these screenshots
 need to be updated.
\end_inset 


\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Subsection

Capturing our first waveforms
\layout Standard

Now that we have several probes hooked to the HAL, it's time to capture
 some waveforms.
 To start the scope, click the 
\begin_inset Quotes eld
\end_inset 

Normal
\begin_inset Quotes erd
\end_inset 

 button in the 
\begin_inset Quotes eld
\end_inset 

Run Mode
\begin_inset Quotes erd
\end_inset 

 section of the screen (upper right).
 Since we have a 4000 sample record length, and are acquiring 1000 samples
 per second, it will take halscope about 2 seconds to fill half of its buffer.
 During that time a progress bar just above the main screen will show the
 buffer filling.
 Once the buffer is half full, the scope waits for a trigger.
 Since we haven't configured one yet, it will wait forever.
 To manually trigger it, click the 
\begin_inset Quotes eld
\end_inset 

Force
\begin_inset Quotes erd
\end_inset 

 button in the 
\begin_inset Quotes eld
\end_inset 

Trigger
\begin_inset Quotes erd
\end_inset 

 section at the top right.
 You should see the remainder of the buffer fill, then the screen will display
 the captured waveforms.
 The result will look something like figure 
\begin_inset LatexCommand \ref{fig:Halscope-demo-4}

\end_inset 

.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-4.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-4}

\end_inset 

Captured Waveforms
\end_inset 


\layout Standard

The 
\begin_inset Quotes eld
\end_inset 

Selected Channel
\begin_inset Quotes erd
\end_inset 

 box at the bottom tells you that the green trace is the currently selected
 one, channel 4, which is displaying the value of the pin 
\begin_inset Quotes eld
\end_inset 

siggen.1.square
\begin_inset Quotes erd
\end_inset 

.
 Try clicking channel buttons 1 through 3 to highlight the other three traces.
\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Subsection

Vertical Adjustments
\layout Standard

The traces are rather hard to distinguish since all four are on top of each
 other.
 To fix this, we use the 
\begin_inset Quotes eld
\end_inset 

Vertical
\begin_inset Quotes erd
\end_inset 

 controls in the box to the right of the screen.
 These controls act on the currently selected channel.
 When adjusting the gain, notice that it covers a huge range - unlike a
 real scope, this one can display signals ranging from very tiny (pico-units)
 to very large (Tera-units).
 The position control moves the displayed trace up and down over the height
 of the screen only.
 For larger adjustments the offset button should be used (see the halscope
 reference in section 
\begin_inset LatexCommand \ref{sec:Halscope}

\end_inset 

 for details).
\layout Subsection

Triggering
\layout Standard

Using the 
\begin_inset Quotes eld
\end_inset 

Force
\begin_inset Quotes erd
\end_inset 

 button is a rather unsatisfying way to trigger the scope.
 To set up real triggering, click on the 
\begin_inset Quotes eld
\end_inset 

Source
\begin_inset Quotes erd
\end_inset 

 button at the bottom right.
 It will pop up the 
\begin_inset Quotes eld
\end_inset 

Trigger Source
\begin_inset Quotes erd
\end_inset 

 dialog, which is simply a list of all the probes that are currently connected
 (Figure 
\begin_inset LatexCommand \ref{fig:Halscope-demo-5}

\end_inset 

 ).
 Select a probe to use for triggering by clicking on it.
 For this example we will use channel 3, the triangle wave.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-5.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-5}

\end_inset 

Trigger Source Dialog
\end_inset 


\layout Standard

After setting the trigger source, you can adjust the trigger level and trigger
 position using the sliders in the 
\begin_inset Quotes eld
\end_inset 

Trigger
\begin_inset Quotes erd
\end_inset 

 box along the right edge.
 The level can be adjusted from the top to the bottom of the screen, and
 is displayed below the sliders.
 The position is the location of the trigger point within the overall record.
 With the slider all the way down, the trigger point is at the end of the
 record, and halscope displays what happened before the trigger point.
 When the slider is all the way up, the trigger point is at the beginning
 of the record, displaying what happened after it was triggered.
 The trigger point is visible as a vertical line in the progress box above
 the screen.
 The trigger polarity can be changed by clicking the button just below the
 trigger level display.
 Note that changing the trigger position stops the scope, once the position
 is adjusted you restart the scope by clicking the 
\begin_inset Quotes eld
\end_inset 

Normal
\begin_inset Quotes erd
\end_inset 

 button in the 
\begin_inset Quotes eld
\end_inset 

Run Mode
\begin_inset Quotes erd
\end_inset 

 box.
\layout Standard

Now that we have adjusted the vertical controls and triggering, the scope
 display looks something like figure 
\begin_inset LatexCommand \ref{fig:Halscope-demo-6}

\end_inset 

.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-6.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-6}

\end_inset 

Waveforms with Triggering
\end_inset 


\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Subsection

Horizontal Adjustments
\layout Standard

To look closely at part of a waveform, you can use the zoom slider at the
 top of the screen to expand the waveforms horizontally, and the position
 slider to determine which part of the zoomed waveform is visible.
 However, sometimes simply expanding the waveforms isn't enough and you
 need to increase the sampling rate.
 For example, we would like to look at the actual step pulses that are being
 generated in our example.
 Since the step pulses may be only 50uS long, sampling at 1KHz isn't fast
 enough.
 To change the sample rate, click on the button that displays the record
 length and sample rate to bring up the 
\begin_inset Quotes eld
\end_inset 

Select Sample Rate
\begin_inset Quotes erd
\end_inset 

 dialog, figure .
 For this example, we will click on the 50uS thread, 
\begin_inset Quotes eld
\end_inset 

fast
\begin_inset Quotes erd
\end_inset 

, which gives us a sample rate of about 20KHz.
 Now instead of displaying about 4 seconds worth of data, one record is
 4000 samples at 20KHz, or about 0.20 seconds.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-7.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-7}

\end_inset 

Sample Rate Dialog
\end_inset 


\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Subsection

More Channels
\layout Standard

Now let's look at the step pulses.
 Halscope has 16 channels, but for this example we are using only 4 at a
 time.
 Before we select any more channels, we need to turn off a couple.
 Click on the channel 2 button, then click the 
\begin_inset Quotes eld
\end_inset 

Off
\begin_inset Quotes erd
\end_inset 

 button at the bottom of the 
\begin_inset Quotes eld
\end_inset 

Vertical
\begin_inset Quotes erd
\end_inset 

 box.
 Then click on channel 3, turn if off, and do the same for channel 4.
 Even though the channels are turned off, they still remember what they
 are connected to, and in fact we will continue to use channel 3 as the
 trigger source.
 To add new channels, select channel 5, and choose pin 
\begin_inset Quotes eld
\end_inset 

stepgen.1.dir
\begin_inset Quotes erd
\end_inset 

, then channel 6, and select 
\begin_inset Quotes eld
\end_inset 

stepgen.1.step
\begin_inset Quotes erd
\end_inset 

.
 Then click run mode 
\begin_inset Quotes eld
\end_inset 

Normal
\begin_inset Quotes erd
\end_inset 

 to start the scope, and adjust the horizontal zoom to 5mS per division.
 You should see the step pulses slow down as the velocity command (channel
 1) approaches zero, then the direction pin changes state and the step pulses
 speed up again.
 You might want to increase the gain on channel 1 to about 20m per division
 to better see the change in the velocity command.
 The result should look like figure 
\begin_inset LatexCommand \ref{fig:Halscope-demo-8}

\end_inset 

.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename halscope-demo-8.png

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Halscope-demo-8}

\end_inset 

Looking at Step Pulses
\end_inset 


\layout Subsection

More samples
\layout Standard

If you want to record more samples at once, restart realtime and load halscope
 with a numeric argument which indicates the number of samples you want
 to capture, such as
\layout LyX-Code

halcmd:
\series bold 
 loadusr halscope 80000
\layout Standard

if the 
\family typewriter 
scope_rt
\family default 
 component was not already loaded, halscope will load it and request 80000
 total samples, so that when sampling 4 channels at a time there will be
 20000 samples per channel.
 (If 
\family typewriter 
scope_rt
\family default 
 was already loaded, the numeric argument to halscope will have no effect)
\the_end