Servo Indexing and Registration - Part 1 - LS Electric L7C &L7P Servo System

?In indexing mode, you tell the drive what you  want it to do by filling in some tables with what   position to go to at some speed and accelerations  and how long to dwell at that location. Then fill   in the next one and the next one, etc., to  build your motion profile. You can loop backward   or forward to any of the 64 possible indexes and  each index can be repeated up to 65,000 times.   The L7C servo system handles  multiple types of indexing moves.   In this video, we’ll cover the absolute and  relative moves, in Part 2 we'll cover blended and   registration moves and in Part 3 we'll cover rotary  moves which have their own unique way of doing things.   Of course, the best way to see how all of his  works is with live examples, so let’s do it.   I’m going to assume you have seen the quick  start videos and you're already familiar with the   DriveCM software – which you can download  for free at AutomationDirect.com. So I’m   going to breeze through a lot of the setup steps.  Check out those videos if you need a refresher.   I’ll go to Setup, Return to Factory setting so  you know exactly where I am starting from. Yes   we really want to do that. Give it a second for  this dialog to go away and it’s done. You can   either power cycle the drive or just hit this guy  to reset the drive processor. Yes we want to do   that. Wait for it to reconnect and we are ready  to go. That ensures that the drive is in a known clean   state before proceeding. Don’t forget to do that. Setup wizard - we want to be online with the drive   and yes we want to read the drive's current  configuration. Auto encoder. We want indexing   mode. We’re doing the linear mode in this  video – we’ll use the rotary mode in Part 3.   You can specify which of the 64 indexes the  drive should start at when you kick off indexing.   We’ll be controlling the starting index with  digital inputs, so we need to turn this off.   Rotation is fine. Let’s change the gearing so that 100,000 pulses   gives us one rotation. The encoder on the motor I  am using has 2 to the 17th pulses per revolution   and we’ll electronically gear that to 100,000  user units per revolution just to make the math   easy in our demo. The linear slide we’ll be  using travels 5 millimeters for each rotation   so now 100,000 pulses will  give us 5mm of travel.   All of this is fine. Using digital inputs, we need to be   able to enable the servo, select a couple indexes,  and start and stop the indexing. I have signals   wired to Input 2 for home and Inputs 7 and 8 for  over travel limits for other demos, so I’ll assign   those just to remind us they are there. We won’t  be using them in this demo but we do need to flip   the sense so they don’t interfere with us. For the outputs, let’s keep an eye on the   origin and the position signals – we’ll use  those in Part 2. I’ll clear out the rest.   I’ll select Homing Mode 35 as the default in  case we need to quickly clear the position   register to zero. That doesn’t actually move the  motor, it just clears the position register.   Write all of that to the drive. Give  it a second and it’s done. And again,   we always reset the drive's controller after making  changes to ensure all loose ends got cleaned up.   Wait for it to reconnect and we are good to go. I put this ruler here and added this black paper   triangle, so we can see how far the slide travels.  I’ll go to jog to move the carriage somewhere near   the center of the slide. And I’ll move the  ruler so it aligns with 100 millimeters.   Let’s go to homing which we set up to Mode 35.  All that does is clear the position register   to zero making this the new origin. Great, we’re all set up so now we can   finally do some indexing examples. Click on this guy to go to the indexing setup.   Let’s do an absolute move to  go to the 100,000 pulse mark   which should be 1 rotation which  should make the carriage move 5mm.   I’ll put the velocity and accelerations at  relatively slow values, so we can see what’s   happening here in the video. We don’t care about  registration right now, and we’ll only do this once,   and let’s dwell at that  position for 500 milliseconds.   Remember that you have to hit the enter key  to get rid of the red which tells you it has   been entered into the drive’s volatile memory.  Hit this button down here if you want it to be   permanently written to the drive so when you  power cycle the drive it's still there.   We don’t care about the next index because  we are going to stop after this move.   All of this get’s written immediately  to the drive, so we are ready to go.   We’ll control the drive from the digital  input panel. This allows us to override   any digital inputs that may be wired to the  drive and create new ones that aren’t like   this start and stop signal we are using here  – they aren’t actually wired to the drive.   Let’s enable the servo’s output, and if  we watch the slide as I toggle the start   signal, yep, it moved the expected 5mm. Perfect.  If I toggle the start again, hmm, nothing.   Why? We told it to move 100,000 pulses, right? No. We told it to go to Position 100,000.   If we bring up the jog panel, we see that we are  at 100,000. So now when we toggle start,   we are telling it to go to the 100,000 position  again. But we are already at the 100,000 position   so it does nothing. That’s an absolute move  – it goes to the position you tell it to.   If we switch that to a relative move  – it now says move an additional   100,000 pulses relative to where you are. If we watch the slide each time we toggle   the start signal, the motor  moves another 5mm relative to where we were.   To get back to zero we could do relative -400,000  pulses. Instead, let’s just do an absolute move   directly to zero. Toggle start and  we are back to where we started from.   Let’s do a relative move, 100,000 pulses –  or 5mm – but this time repeat that 3 times.   And let’s dwell for 2 seconds and then make the next  index, Index 1. We’ll have Index 1 return to   Absolute Position 0 at a speed of 1 million pulses  per second. And I’ll speed up the accelerations   too. So we should move rapidly back to zero. I’ll toggle start and we see the three 5mm moves   execute, then a 2-second dwell, and then the  Index 1 move rapidly back to zero.   Notice that the dwell only affected  the time between Index 0 and 1.   It didn’t affect the time between the three  iterations of Index 0. Those executed one right   after the other. Just something to be aware of. Do you have to go to the next index? Nope. You   can jump to any index you want. And  you can start at any index you want.   For example, in the setup wizard we only setup  two of the 6 possible index select bits. You can   see from this table in the user manual that when  none of the 6 bits are enabled the drive starts   at Index 0. When the first bit is enabled  it starts at Index 1. When the second one is   enabled it starts at Index 2 and when both of  those are enabled it starts at Index 3. When   they are all enabled, it starts at Index 63. So  it’s selecting indexes based on a binary pattern.   Since we are only using two of the index  select bits, we can only select indexes zero   through three before the pattern repeats. But any one of those four starting indexes   could jump to any of the other indexes  which can jump to any other index   and so on. So even though our two selector bits  only allows us to have 4 starting points, that   doesn’t limit the number of total moves at all.  You still have all 64 indexes available to you.   And remember – if you run out of digital inputs,  all 6 of the index select bits can be controlled   via Modbus. Don’t forget you have that option. One side note - if you scroll through the indexes   all the way up to Index 64 and then back  again, your screen will be blank.   Why? Well, you just asked the drive to transfer  a lot of information and it takes a while to   catch up. When I timed it, it took around 45  seconds. I don’t have that kind of patience,   so I just toggle the drive offline and then  back on again to quickly refresh the display.   It’s important to know that the starting  index we specified using the digital inputs   is only read when the start signal toggles.  So, you can change these to get ready for your   next sequence while the move is in progress.  It won’t impact the current move at all.   Of course, if you need to stop the  move just toggle the stop signal.   The absolute and relative moves are  really powerful all by themselves.   But the L7C drive doesn’t stop there. It also  provides a blended move and the ability to   move relative to a registration mark and it has  moves specifically designed for rotary motion.   Join us in Part 2 and Part 3 where  we’ll see how all of that works.   Meanwhile, click here to learn  more about the L7C Servo System.   Click here to learn about AutomationDirect’s  free award-winning support options and click   here to subscribe to this YouTube  channel and hit that little bell icon   so you will be notified when we  publish more videos like this one.