We're back at another episode of problem solved. I'm Jake, and I'm Carlton, and today
we're going to hit on the topic of internal positioning on a KEB Drive.
Let's do this.
So Carlton, tell us. What is internal positioning?
Internal positioning can be described as using a standalone VFD to perform specific
positioning profiles without the use of a PLC or motion controller.
So how is it used?
Inside every closed-loop drive from KEB is the capability to program up to
32 indexable positions within the drive. And for each of those positions you have
the opportunity to customize a set speed and positioning modes such as relative
or absolute positioning within each of those indexes. So what are some of the
capabilities of this internal positioning? Yeah Jake, there are
essentially three different modes that can be used with the 32 indexable
positions. The first is considered a "Stop After Each," which at the onset
of a positioning move requires a positioning start command from a digital
input, and once that move is completed a new positioning command input is
required before moving to the next chronologically sequenced indexing
position. The second mode is an "Auto Index," which behaves very similar to the
"Stop After Each" index, except requires only one positioning command at the
onset of the sequence, then the positioning module will automatically
sequence through the 32 bit positions chronologically. The third positioning
mode is considered a "Selectable Indexing" mode which will allow you to select any
of the 32 indexing positions in any order that you want. So you can move
between position 4, and position 8, back to position 2, to position 23, to position
7, and move to any order that you would like.
So, what are some applications where this would be beneficial? Yeah Jake, so this
internal Positioning module would really be best suited for applications with single
axis motion or sequential motions such as a rotary wheel or a conveyor.
Applications that require complex coordinated motion or multi axis motion
would really be best suited to be driven with a PLC or a motion controller.
So let's dive into it. Why don't you show us how it all works. Yeah let's do it.
We're here with our S6 demo and we're gonna be diving into some programming
with internal positioning. On the S6 drive, for now we're gonna bypass the
startup of the S6, just because we've done that in a previous problem solved
video. So for now we're gonna dive right into the programming for the positioning
module on the S6. So let's get to it.
So here in COMBIVIS 6 I've connected my
drive, and I've created this internal positioning parameter list that we're
going to be using for this internal positioning module with the S6 drive.
Inside this internal positioning parameter list we see a set of
parameters here that I have added before the start of this video. Taking a brief
look at our parameter list, we have our read/write designator, our IDText,
our parameter name, the offline value column, which contains the user-defined values
that are stored inside the parameter lists, our online value column, which are
real time values that are only displayed when connected to a KEB drive, and our
comments section. We can write the offline value to the online value using
the download list to device option that we will employ later in this video.
The top four parameters here you'll see these are "RO" for Read-Only, and these
are "ST" parameters. So these are status parameters. We have the status word, brake
control status, state machine display, and position actual value.
So these are parameters that will just allow us to monitor the performance
of the drive during the programming and then during the positioning run.
Moving on from the status parameters,
we are going to look at our control parameters here. We have
our mode of operation, our position source, our brake control mode, and
control word internal for the drive. We were in velocity mode to do the startup
of our S6, but we are going to be in profile positioning mode here for
internal positioning. We have channel "A" set as our position source. Wo we can use
the encoder feedback for positioning. We are going to change our brake control
mode to applications. So that when the drive is enabled properly the brake will
automatically open and the brake will then close when the drive is disabled.
We do not have to operate that through the control word.
As of right now, we have an empty control word,
but we'll describe how that will be manipulated here in our
next set of parameters. Looking at the DI parameters, we have our CA input CA mask
CB input, and CB mask. So these four input parameters are inputs and masks for the
control word. So since we are not using a PLC in this case, we will actually use
digital inputs - specifically digital input 1 and digital input 2 as shown
here - in the CA and CB inputs to control aspects of our control word to enable
the drive for operation in positioning. So input 1 will switch the drive on,
enable the voltage, and enable operation for the drive to move. Activating digital
input 2 will serve as our positioning command as that is operation specific input 4.
VL 20 is our target velocity parameter. We are going to set that to 0 RPM
so that when the drive is not actively positioning it will hold at a
zero speed position and not rotate continuously. Parameter PS 38, positioning
module, is really important in this application as this sets the positioning
module for the drive. So just opening up this parameter we can
see the options we have for this positioning module. So for the
positioning module we will select "index selection" which will allow us to utilize
our 32 indexable positioning points. Our indexing mode is "auto indexing" mode and
we also have "Stop After Each" index if desired.
For relative positioning you can either choose to perform relative positioning
based on the set position that you have, or the actual position that is being
measured at the encoder. For our sake, just for this test, we'll use the actual
position. And you can also use round table positioning mode, but we will have
that off since we won't be using round table positioning in this case. But that
is an option for you if you so desire. So exit out of the positioning module
dialog box. And the parameters that we have discussed thus far in this
parameter list represent the formation of the shell of the internal positioning
module in the S6 drive. We have set our profile positioning mode. We have set our
positioning source to the encoder. We have configured our controller to be
controlled via digital input. We have set our positioning module for index
selection. And now the only thing left to do is to program our actual indexing
positions. So if we scroll down. The bottom half of this parameter list
actually represents the program indexing positions. As you can see here in the
comments section, I have indicated index 0 through index 5. So 0 through 5, that
makes for 6 indexing positions. As we've stated previously in this video there
are up to 32 programmable indexing positions in the S6 drive, but
just for this testing purpose we are going to only use 6 positions, just for
simplicity's sake. So each of these indexes are just copies of one another.
But we can just kind of break apart what each of these entails in programming
each of these indices. So looking at index 0. The first parameter we see is
PS39 index position. The value of this index position may seem rather large and
a little bit confusing to you at first. However the S6 drive actually utilizes
a 16 bit incremental resolution for every feedback device that is connected
to the drive. What that means is, for any feedback device connected to the drive
one revolution of that of that device corresponds to 65,536 increments inside
the drive software. So this large value if you divide that by 65,536 equates to
30 revolutions. So this is just moving 30 revolutions from its starting point or
zero position. The second parameter, PS40 index speed represents the speed at
which this program position is obtained from the drives previous position.
PS41 index end speed represents the speed at which the drive will obtain at the end
of the positioning move. We always want this set to zero so that when the drive
reaches this position, the drive will reaches zero speed. The fourth parameter
PS 42 next index shows the parameter that is next up in the sequence of
positioning. In the case of our testing, we are using the auto indexing
positioning mode. So once the index 0 position is obtained, the drive will
automatically start to sequence to the index 1 position. The fifth parameter is
PS43 indexing mode. And this is where you can select "absolute" versus "relative"
positioning. For the case of our test and our six indexes we are going to select
absolute positioning mode for all of them. For your setup you can choose
absolute or relative for any of your indexes and use them interchangeably.
Once you finalize the programming for your index 0, you can copy and then just
gently tweak the programming for the the following indexes that you need for your
positioning. And once you incorporate all of the indexes that you need, you are
ready to download the parameter list and start your positioning. So now that we
have added all of our indexes together with all of our programming, we're going
to go up to the download function, "down the list to device." We will click yes.
Now we'll download into the drive and that is successful.
Now we will test the positioning.
Now that we have downloaded the internal positioning program into
the S6 drive, we are ready to test with our servo motor here. So in order to test
we are going to enable our STO inputs. Based on our control mask, our input one
will activate our control and release our break. And now our motor is ready to
run and we are ready to initiate the programming sequence. So now that the
control word is set and the break is released activating digital input 2 will
initiate the auto index positioning command. So here we go.
And that is an example of the auto indexing mode within the internal
positioning module of the S6 drive. we can also demonstrate the stop after each
index positioning mode within the internal positioning module of the S6.
To do this, we will scroll up and modify our positioning module parameter inside the drive.
We are going to change our index mode to "Stop After Each" index.
And then click OK
And we can see that this parameter was accepted in the drive.
For this positioning mode we are actually going
to utilize the scope function of the COMBIVIS 6 software. This scope was created
prior to the video and will allow us to monitor and record three parameters
relevant to our positioning profile. We have ST33 position actual value,
RU18 digital input state, which will show us when a positioning command is given,
and PS 47 active index, which shows us the active index position in the module.
Now that we have the scope created we are going to go start scope.
And then we will begin our positioning.
Now that we have reached index 5 we are going to go
ahead and stop our scope. And this is the recorded data that we have obtained from
the positioning. This blue line, or curve that we see here, represents the
positions that were obtained from our indexes. The magenta steps are the
different index positions and active index that was obtained. And these orange
pulses represent the positioning commands that were given inside the
drive. And just remember from the program we created, we set the target velocity to
be 0 rpm. So when the positioning is completed, as it is now, the drive will
hold a zero speed awaiting a new command.
So thanks Carlton for taking us through
the steps on internal positioning on a KEB Drive. If you liked this video, then like
and subscribe, follow us on social media, and we look forward to making more
problem solved videos for you in the future.
Have a great day.