Servo SureServo2 Pro Scope Function Quick Start - from AutomationDirect

And it’s super easy to use. Let’s put the encoder’s pulses on channel 1 – the yellow channel. And the position in Pulse User Units on channel 2. And let’s change that to red to give us some contrast. Remember that while the Servo motor’s encoder has over 16 million pulses per revolution, the drive defaults to 100,000 user pulses input – which we call “PUU” - to get one revolution via the electronic gearing. There’s a whole video showing you how to use electronic gearing, so we won’t get into that here. Each of the eight channels has resources allocated to display 16-bit numbers. The scope recognized that we are asking it to display a 32-bit number, so it automatically closed out the channel 3 and gave those resources to channel 1 so it could display this 32-bit number. And it also closed out channel 4 and gave its resources to channel 2 – another 32-bit number. These check marks tell us these are 32-bit channels. If I manually turn that off, then channel 3 becomes available, but that will mess things up so let’s turn I back on. Channels 3 or 4 can only be used for 16-bit numbers or to augment channels 1 and 2. These channels work the same way – you get four 16-bit channels or you can combine 5 and 7 and/or 6 and 8 to get 32-bit channels. Let’s collect 20 seconds of data, disable the unused channels, and hit run and rotate the motor shaft roughly one full rotation, then another full rotation, then back one rotation, and another. Then hit stop. This button automatically optimizes the display. We see the actual encoder on the motor climb to 16 million, then wrap back to zero as we rotate past one full revolution. Exactly what we expect to see. If I click to put a cursor at the start of one of those cycles and then move my mouse to the start of the next cycle, we see the position changed the 100,000 pulses that our electronic gear ratio is set to. And it keeps counting up while the encoder wraps back to zero. Looks like it started here and went up to here – which are the two revolutions we did. Perfect. So this column is the scale for the yellow trace, while this one is the scale is for the red trace. We can click on this guy to make all scales the same. Now the couple hundred thousand of the position data is dwarfed by the 16 million sizes of the encoder data. Click on this guy to get back to independent scales. Or click on this guy to optimize the display. The independent axes are a huge help when you are trying to compare traces with little numbers with traces that have big numbers. You can zoom in and zoom out using these guys or you can draw around the area you want to zoom in to. And this keeps track of changes you make so you can quickly get back to a previous screen. Let’s do another example. I set up the drive in position register mode to automatically rotate this 4-pound pulley clockwise 4 revolutions, pause for half a second, rotate counter clockwise for four revolutions, wait half a second and then repeat that indefinitely. The first path is set up to accelerate and decelerate over 15 milliseconds. The second path is set to ramp over 250 ms. Check out the Position Register Mode video to learn how to set all that up. I haven’t tuned this drive yet, but when I enable the servo and trigger the path, to the naked eye everything seems to be working fine – right? Let’s find out. Let’s have the scope track the commanded position which is what we told it to do and also monitor the actual position which is the same trace that we had in the last demo. I also have the commanded speed and actual speed being tracked but not shown yet. Let’s run the scope and I’ll enable the servo for a few cycles. Ok, that’s enough for now. Stop the servo and stop the scope. I’ll hit this button to optimize the display and this one to get them on the same scale. We’re looking at position and sure enough the commanded position changed from zero to 400,000. But the actual position overshot what we asked for! Do you want the bit on your CNC missing the mark by this much? Probably not! Most people will simply slow the system down for better accuracy. We can see that on the second path where we had slow ramps – yep, no overshoot there! Does that mean we have to give up speed to get accuracy? No, it doesn’t. Before I show you how to fix that, let’s look at the speed command and actual speed. I’m going to optimize the display to expand everything to full screen to make it easier to see. We see the speed accelerated up to speed in around 80 or 90 ms – we asked for 15. And it overshot the 1500 RPM we asked for in an effort to make up for the lost time and try to hit the position in time. We also see the purple actual speed didn’t track the blue commanded speed very well at all, did it? We can see on the path with slow ramps, that it didn’t quite finish the 250ms acceleration ramp we asked for before it had to start decelerating. So that tells us our ramps are too long – we’re never getting up to speed which means we are wasting time. We will want to speed up those ramp times a bit but we don’t know how much we can speed them up until we get rid of the overshoot issue. So, let’s see if we can fix the position overshoot issue by doing an auto tune. There’s a whole video showing you how to do that, so I’ll just fast forward through that for this video. Ok, I ran auto tune – it took a whole 80 seconds to complete. Let’s update the parameters and see if things look better now. Run the scope, execute a few cycles of our motion, stop the scope, and zoom in. And look at that! The red actual position gives us a nice smooth landing with no overshoot. Perfect! And if I bring back up the speed command and the actual speed we see they are tracking each other perfectly now. Yeah, auto tune on the SureServo2 drive is one of the best I’ve ever seen. It does an amazing job. So how cool is that? Using this scope function, you can actually see what’s going on and make intelligent decisions about how to fix things without having to resort to the trial and error guessing game. The insight this scope tool gives you into how your system is working is incredible. For example, could you now go in the PR mode configuration and start tweaking loop gains and watching in real-time how that impacts your system? Sure! Again, no guessing – you see immediately the impact each change has on your system in real-time. And there are so many other things you can monitor, you are really only limited by your imagination. It’s crazy how much visibility this gives you into exactly what your system is doing. There are a few things to be aware of. First, you CAN monitor digital I/O – just know that it is a combination of all the bits. So if digital input 0 changes, then the trace will only change by 1. But if digital input 8 changes it will change by 256. If they both change the trace will change by 257. Can you also monitor the individual bits? Sure! Just double click on the data box and you see a breakout of all of the individual bits for ANY parameter, not just the digital I/O. It automatically shows you all 32 bits if that’s what you are looking at. And if you double click again, you see the hex version of the data. Double click a third time to clear the display. You can save the scope data to disk as just the scope data OR scope data AND parameters. That way when you load the scope data using this guy, you know the drive is in the exact same state as when you captured the scope trace. Those are binary files so you can’t import them into a spreadsheet, but look at this. If you right-click on the scope, you get a menu where you can take a screenshot and save the scope as a text file that CAN be imported into excel. It looks like this: where you see the software version, what each channel was recording and the data for each channel. When I import it into excel it looks like this. One caution: this dumps the entire buffer. This one was 160 thousand lines long, so be patient – it takes a while for the PC to transfer or really do anything with this much data. These guys simply enable or disable all of these channels. You can select how you choose each item to view here. You can select via the normal English terms we’ve been using, or you can select what you want to display by parameter address, or by parameter group and number. This one allows you to use the scope to plot any of the things you can see on the drive's LED display. Table 8-3 in the user manual lists all of those LED displays. You just enter the decimal number of the display that you want to monitor on the scope. The cursors are simple – click at one point. Now when you move the cursor it tells you the difference between the point you clicked on and where you are now for each trace. This says to keep the most recent 40 seconds of data for example. And this says sample the data 8000 times per second. You can double the sample rate, but you lose half the channels when you do that. Change the color of each trace by clicking on the color box. Change the scope properties by clicking on preferences where you can disable gridlines, change the color of the grid, change auto-adjust, etc. If you need more scope area, then unpin this side of the scope so it only pops out when the mouse cursor is over there. If you want it to stay up, then just re-pin it. Of course, you can zoom in, zoom out, print, and clear the screen. You can also select the background color and the scope screen color. Just know that when you save data, it only saves the data, not the formatting. So when you open a saved file, it comes up in the current color scheme. Well that ought to be enough to get you started with the SureServo2 Pro Scope function. It really is amazing that this software contains so many high-end features like this and it is still completely free. That’s crazy! Just go to AutomationDirect.com and search for SureServo2 Pro to download it right now. Click here to see more SureServo2 videos. Click here to subscribe to our YouTube channel so you will be notified when we publish more videos like this and click here to learn about AutomationDirect’s free award-winning support options.