View source for AXY:path-PLS

<big><span style="color: red">'''Replaced by NEW PLS article - [[Programmable Limit Switch]]'''</span></big>

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= Introduction =

The path-PLS is associated with the motion nodally. Thus, instead of enabling/disabling using the command '''PLSEnable''', the PLS will be automatically enabled at motion start and disabled at motion end. The motion path distance from the motion start, along the motion path, is the '''PLSsource''' variable of the PLS. Depending on the various interpolation modes, different '''PLSsource''' variables can be used:

* Path length in position user units (e.g., mm) In case of straight line (MOVES) motion it is just a distance for the starting position. In case of joint interpolated motion (MOVE) there is no physical meaning of such a distance and in circular interpolation, we can choose between arc length and the angle from the starting point.
* Percentage of the motion path from the start. This variable has the advantage that it is universal , means that it can be used in all motion types. However it has no physical meaning. Percentage can be very useful in motions having dominant orientation part.
* Time elapsed from the motion start. This can be useful in certain application but can be applicable in time-based profiles only (PrfType = 2).
* X,Y,Z coordinate. This is somehow a combination of path length and the percentage of the path, it has an advantage that it is a comfortable way of implementing application constrains. Also it can be applied to any type of motion interpolation. However, using it can cause multiple triggering of a same PLS position during one movement.<br/> 

<br/>{{Note|}}
::*All properties and behaviors of the path-PLS are identical to the regular PLS except when it is explicitly noted.

::*Contrary to the one-dimensional PLS, the path-PLS can be triggered using command values only. There are no feedback path-PLS sources.

::*Due to the complex nature of advanced interpolation path forms, the path-PLS is not applicable to these interpolation types.

::*The user must set the PLS output to the initial state. From then on, when the PLS is enabled, it will toggle the output. Disabling PLS does not affect the state of the digital output in any way.

= Implementation =

Path-PLSs can be defined in the same way as one-dimensional PLS.  Contrary to the one-dimensional PLSs the path-PLS can be activated only when explicitly given in a movement statement. Some of [[MC-Basic:element.PLSSOURCE|Axis.PLSSource]] are especially to the path-PLS.

== PLS Properties and Commands ==

[[MC-Basic:COMMON SHARED ... AS PLS| Common Shared <pls> as PLS {<element>} <io> {Hwassistance = on/off} ]]

Command for PLS language object definition. Can get an element as robots or groups. Joint-based or non-robot based PLSs are not allowed. Path-PLSs are PLSs defined on elements that are robots and not axes.

[[MC-Basic:pls.PLSENABLE|PLSENABLE]]

Enabling of path-PLS is done through nodal assignment only. Thus, setting this variable will return an error except when PLSsource = XCOO/YCOO/ZCOO. Querying this value will return the current state of a path-PLS depending on the movement being executed.

[[MC-Basic:pls.PLSREPEAT|PLSREPEAT]]

Behaves the same as the regular PLS, but works on the selected '''PLSsource''' instead of the axis position.

[[MC-Basic:pls.PLSRELATEDTO|PLSRELATEDO]]

Flag used by '''oriented''' PLS-sources to define whether the PLSposition[*] is computed relative to the start(0) or to the target(1). For example, in '''PathLength''' it indicates whether the length is measured from the start or from the end of the motion. Default value is 0. If nothing is specified, all path-specific variables will be computed from the start.

[[MC-Basic:element.PLSSOURCE|PLSSOURCE]] <br/>
The following table summarizes the types of '''PLSSource'''.
{|border="1px" cellpadding="3" cellspacing="0" 
| '''Source Name'''
| '''One-dimensional<br> PLS'''
| '''Path-PLS'''
| '''Description'''
| '''During<br>Blending'''
| '''Related to<br>Start/Target'''

|-
| POSITIONCOMMAND
| ✓ 
| no
| Axis position command 
| rowspan="6"|Coordinate
| rowspan="6"|No

|-
| POSITIONFEEDBACK 
| ✓ 
| no
| Axis position feedback

|-
| POSITIONEXTERNAL 
| ✓ 
| no
| External position 

|-
| Setpoint1
| no
| ✓ 
| X axis position (SetPoint{1} value). 

|-
| Setpoint2
| no
| ✓ 
| Y axis position (SetPoint{2} value).

|-
| Setpoint3
| no
| ✓ 
| Z axis position (SetPoint{3} value).

|-
| PathLength
| ✓ 
| ✓ 
| Length of the path in user units.
| rowspan="3"  | Single
| rowspan="3"  | Yes

|-
| PathPercentage
| ✓ 
| ✓ 
| Percentage of the path.

|-
| PathTime
| ✓ 
| ✓ 
| Time duration in ms.

|}
<br/>

[[MC-Basic:WITHPLS|WITHPLS]]

Nodal assignment of path-PLS used for enabling path-PLS during motion. The WithPLS command specifies the PLSs that will be enabled during execution of the given motion and disabled when the motion ends. 

===== Related Properties and Commands =====  
*[[MC-Basic:pls.PLSENABLE|PLSENABLE]] 
*[[MC-Basic:pls.PLSREPEAT|PLSREPEAT]] 
*[[MC-Basic:pls.HWASSISTANCE|HWASSISTANCE]] 
*[[MC-Basic:pls.PLSHYSTERESIS|PLSHYSTERESIS]] 
*[[MC-Basic:pls.PLSAXISNAME|PLSAXISNAME]] 
*[[MC-Basic:pls.PLSEMENTNAME|PLSELEMENTNAME]] 
*[[MC-Basic:pls.PLSPropagationEnableDelay|PLSPropagationEnableDelay]] 
*[[MC-Basic:pls.PLSPropagationDisableDelay|PLSPropagationDisableDelay]]
*[[MC-Basic:pls.PLSPropagationDelay|PLSPropagationDelay]] 
*[[AXY:PLS On/Off delay| PLS On/Off delay]] 
*[[MC-Basic:pls.HWIOtime|HWIOtime]]
*[[MC-Basic:pls.PLSOUTPUT|PLSOUTPUT]]
*[[MC-Basic:pls.PLSPOLARITY|PLSPOLARITY]]
*[[MC-Basic:pls.PLSPOSITION|PLSPOSITION]]
*[[MC-Basic:pls.PLSdelaytime|PLSdelaytime]]
*[[MC-Basic:CREATEPLSDATA|CREATEPLSDATA]]
*[[MC-Basic:DELETEPLS|DELETEPLS]]
*[[MC-Basic:PLSLIST|PLSLIST]]

== Path Percentage and Path Length ==

PLSsource can be '''PATHPERCENTAGE''' and '''PATHLENGTH'''. These are special types of position sources, both discontinuous variables that changes their values abruptly at the point where two movements are executed one after another. 

Example: '''PATHPERCENTAGE'''
<pre>
MOVE A  PLSSOURCE 0→100
MOVE B  PLSSOURCE 0→100
</pre>
At point A the source changes its value from 100 to 0.<br/>
<br/>
Example:  '''PATHLENGTH''':
<pre>
MOVE A  PLSSOURCE 0 → L1
MOVE B  PLSSOURCE 0 → L2
</pre>
At point A the source changes its value from L<sub>1</sub>  to 0.<br/>

During joint-interpolated (MOVE) movements '''PathLength''' is not relevant since the physical dimensions of such a variable are non-existent. However, the option of using '''PathPercentage''' remains. For '''PathLength''' descriptor, if the units are not homogenous, the value in aggregate units is used. For CIRCLE interpolation this will be the angle on the circle-arc from the starting point.

For''' PathPercentage''' all values of '''PlsPosition[]''', '''PlsHysteresis''' and '''PlsRepetition''' are in percentage units on a scale of 0 to 100. All values that are negative or above 100, are used as 0 or 100.

Every local '''PLSSource''' can cause a change in I/O state at the start of the movement depending on the '''PLSPolarity''' definition (see [[MC-Basic:pls.PLSPOLARITY|PLSPOLARITY]]). The I/O will appear at the first sample of the movement without time delay, meaning that '''PlsDelayTime[0]''' or '''HWIOtime[0]''' will be equal to 0.

{{Note | In an instance of two movements in which the first ends with '''VFinal > 0''', there will be no setting to '''!PLSPolarity''' at the start of the followed movement. The next toggling is done at the first PLS position of the second movement (see Example 7 below).}}<br/>

== PathTime  ==

The time-based source is applicable in time-based profiles only [[MC-Basic:element.PROFILERTYPE|prftype=2]], else an error is returned.

{{Note | There are two categories of PLS-sources '''coordinate''' and '''single'''. The only difference is observable during blending. The coordinate PLS-sources trigger the PLS output once per PLS-condition independently how many individual motions caused it. The single PLS-source trigger the PLS output as many times as the number of movements involved in the blended motion (could be maximally 2) }}<br/>
{{Note | In case of  '''PLSsource''' from type length, percentage or time there is no continues in toggling no matter if the PLS was global enabled using '''PLSEnable''' or local using '''WithPLS'''. }}<br/>

== Setpoint1, Setpoint2, Setpoint3 ==
SetPoint sources are the virtual Cartesian axes, defined in the robot world frame (i.e., setpoint). Not relevant for Group without a defined kinematics. Those sources can be tracked independently at a specific movement (using ''' PLSEnable ''').

During '''Conveyor Tracking''', values of '''Setpoint1, Setpoint2, Setpoint3''' will assume values on absolute robot coordinates (i.e., '''setpoint, here''') and not robot frame coordinates moving with the robot.

During joint-interpolated (MOVE) movements, values of  '''Setpoint1, Setpoint2, Setpoint3''' will be linearly interpolated between the samples. Therefore, depending on the sample rate and velocity, an interpolation error may occur.

== PLS Tracking During Proceed Command ==
PLSSource can be defined as global or local, and as absolute or relative.  
* '''Absolute''' - PLSSources that are positions in the spcase - PCMD , PFB, SetPoint1, SetPoint2 and SetPoint3.
* '''Relative''' - PLSSources that depend on the current movement as PLSLength, PLSPercentage and PLSTime.
* '''Global''' - PLSSources that are operated by the command '''PLSEnable'''.
* '''Local'''  - PLSSources that are connected to a specific movement, meaning they are operated by the command '''WithPLS'''.

The following table shows how the PLS will be tracked during proceed command:
{|border="1px" cellpadding="3" cellspacing="0" 
| '''PLSSource '''
| '''Absolute'''
| '''Relative'''

|-
| '''Global'''
| Tracking 
| Track will start from first PLS position at the buffer.

|-
| '''Local'''
| Tracking
| No tracking as the original path is no longer relevant.

|}
<br/>

== Notes  ==

{{Note | Path-PLS feature is not applicable for JOG, DELAY , PASS and DOPASS commands. An error will be returned.}}<br/>
{{Note | Stop command disables all PLSs given in the currently executing motion.}}
<br/>
Refer to: [[PLS Timing Issues]]

= Examples =

== Example 1 ==

Using length of the path (distance from starting point) for the position source. Note the default value of PLSRelateTo is zero, therefore all given PLSposition values are computed from the motion start.

<pre>
common shared GXY as group of axnm = A1 axnm = A2 of XY
common shared P1 as pls GXY Sys.Dout.1
common shared P2 as pls GXY Sys.Dout.2
common shared P3 as pls GXY Sys.Dout.3
CreatePLSdata 2 P1  
CreatePLSdata 2 P2 
CreatePLSdata 2 P3 

P1.plsposition[1] = 10
P1.plsposition[2] = 90
P2.plsposition[1] = 10
P2.plsposition[2] = 90
P3.plsposition[1] = 10
P3.plsposition[2] = 90

GXY.PLSsource = PathLength 
GXY.en = 1
MOVES {100,0} WithPLS = P1
MOVES {0,100} WithPLS = P2
MOVES {0,0}   WithPLS = P3
</pre>

[[File:Axystems;Path-pls-example1.png|600px]]

== Example 2 ==

Using Cartesian axis limits for position source (Setpoint1).

<pre>common shared GXY as group of axnm <nowiki>= A1 axnm = A2 of XY</nowiki>
common shared P1 as pls GXY Sys.Dout.1
CreatePLSdata P1 2 
<nowiki>P1.plsposition[1] = 10</nowiki>
<nowiki>P1.plsposition[2] = 100</nowiki>
GXY.PLSsource = Setpoint1
GXY.en = 1
MOVES {0,0} 
MOVES {200,200} WithPLS = P1
</pre>

<gallery widths=400px heights=400px> Image:Axystems;Path-pls-example2.png | DOUT 1 is triggered when the path passes value X = 10 and X = 100 </gallery>

== Example 3 ==

Using path percentages to switch on/off an output during the motion. Two PL-positions are defined: one at 0% (motion start) and one at motion end (100%). Practically, this means the output will be ON during execution of the entire motion and will be switched OFF at the motion end. The default value of PLSRelatedTo determines that the percentage is calculated from the motion start.

<pre>
common shared GXY as group of axnm <nowiki>= A1 axnm = A2 of XY</nowiki>
common shared P1 as pls GXY Sys.Dout.1
CreatePLSdata P1 2 
<nowiki>P1.plsposition[1] = 0</nowiki>
<nowiki>P1.plsposition[2] = 100</nowiki>
GXY.PLSsource = PathPercentage 
GXY.en = 1
MOVES {0,0} 
MOVES {200,200} WithPLS = P1
</pre>

[[File:Axystems;Path-pls-example3.png]]

== Example 4  ==

Switching between two movements ('''not blended'''). If two motions with the same PLS are executed one after another, the PLS will be switched OFF within duration of one sample where the path-percentage changes from 100% (first motion) to 0% (second motion). The PLS remains enabled throughout the execution of the motion.

<pre>common shared GXY as group of axnm <nowiki>= A1 axnm = A2 of XY</nowiki>
common shared P1 as pls GXY Sys.Dout.1
CreatePLSdata P1 2 
<nowiki>P1.plsposition[1] = 0</nowiki>
<nowiki>P1.plsposition[2] = 100</nowiki>
GXY.PLSsource = PathPercentage 
GXY.en = 1
MOVES {0,0} 
MOVES {200,200} WithPLS = P1
MOVES {300,300} WithPLS = P1
</pre>

<gallery widths=460px heights=400px>
Image:Axystems;Path-pls-example4_1.png|At start of the first motion the output is switched ON, at its end it is switched off. Immediately after it the first sample of the second motion will switch the output back on and the output will be ON all the time until the second motion ends.
Image:Axystems;Path-pls-example4_2.png|At the last sample of the first motion the output is switched off. And at the first sample of the second motion the output is switched on again.
</gallery>

== Example 5 ==
Switching between two '''blended''' movements.

The example shows the system behavior when the PLS-Source is of '''single''' type.
During actual blending (time when two motions are executed simultaneously) the system considers two independent variables passing the given PLS values (simultaneously).

* path length (or a percentage of it) of the '''first''' motion is checked if passing the PLSpositions
* path length (or a percentage of it) of the '''second''' motion is checked if passing the PLSpositions

Thus, if two motions with the same PLS (having pos. on 0%,100%) are blended, the PLS output will be switched OFF during the "double movement" phase (when both motions are superposed/blended).

<pre>common shared GXY as group of axnm <nowiki>= A1 axnm = A2 of XY</nowiki></pre>

<pre>
common shared P1 as pls GXY Sys.Dout.1
CreatePLSdata P1 2 
<nowiki>P1.plsposition[1] = 0</nowiki>
<nowiki>P1.plsposition[2] = 100</nowiki>
GXY.PLSsource = PathPercentage
GXY.BlendingMwthod = 2
GXY.BlendignFactor = 90
GXY.en = 1
MOVES {0,0} 
MOVES {200,200} WithPLS = P1
MOVES {300,300} WithPLS = P1
</pre>

<gallery widths = 400px heights = 400px>
Image:Axystems;Path-pls-example5_1.png| Output is switched off (toggled) at the beginning of the second motion (before the first is finished) and toggled back on by the end of the first motion.
Image:Axystems;Path-pls-example5_2.png| AT the beginning of the double-motion phase thee PLS triggered by the beginning of the second movement is switching the output OFF. The end of the first motion that coincident with the double-motion end switches the output back ON (toggle).
</gallery>

== Example 6 ==

Switching the PLS on same distance from beginning and the end of the motion.

<pre>
common shared GXY as group of axnm = A1 axnm = A2 of XY
common shared P1 as pls GXY Sys.Dout.1
common shared P2 as pls GXY Sys.Dout.2
common shared P3 as pls GXY Sys.Dout.3
CreatePLSdata P1 2 
CreatePLSdata P2 2
CreatePLSdata P3 2

P1.plsposition[1] = 10
P1.plsposition[2] = 70
P1.plsRelatedTo   = 0

P2.plsposition[1] = 10
P2.plsposition[2] = 70
P2.plsRelatedTo   = 1

P3.plsposition[1] = 10
P3.plsposition[2] = 70
P3.plsRelatedTo   = 0

GXY.PLSsource = PathLength 
GXY.en = 1
MOVES {100,0} WithPLS = P1
MOVES {0,100} WithPLS = P2
MOVES {0,0}   WithPLS = P3
</pre>

<gallery widths = 400px heights = 300px>
File:Path pls example6 2.PNG| Switching the output 10mm or 70mm after start point or before target depends on plsRelatedTo definition.
</gallery>

== Example 7 ==
Shows the difference in serial movement once that are blend with '''Vfinal'''>0 . In both cases the '''PLSsource''' is from type percentage.

'''Serial movements with VFinal > 0'''
<pre>
 common shared pathpls as pls GXY sys.DOut.1 HWAssistance =  TRUE

 createplsdata 1 pathpls 
 pathpls.plsposition[1] = 100
 pathpls.plspropagationdelay = 0
 pathpls.plspolarity  = 0
 plssource = pathpercentage

 sys.DOut.1 = 0
 move {100,100} vcruise = 100 vfinal = 100
 move {100,0} vcruise = 100   vfinal = 100 withpls = pathpls
 circle angle = -90 circlecenter = {0,0}   vcruise = 100 withpls = pathpls
</pre>

[[File:Axystems;Pls with vfinal.png|caption|600px]]
Shows axes pcmd , IO (X20) and PLSEnable(X40)

<br/>
'''Serial movements with VFinal = 0'''
<pre>
 common shared pathpls as pls GXY sys.DOut.1 HWAssistance =  TRUE

 createplsdata 1 pathpls 
 pathpls.plsposition[1] = 100
 pathpls.plspropagationdelay = 0
 pathpls.plspolarity  = 0
 plssource = pathpercentage

 sys.DOut.1 = 0
 move {100,100} vcruise = 100 
 move {100,0} vcruise = 100    withpls = pathpls
 circle angle = -90 circlecenter = {0,0}   vcruise = 100 withpls = pathpls
</pre>

[[File:Axystems;Pls with vfinal zero.png|caption|600px]]
Shows axes pcmd , IO (X20) and PLSEnable(X40)

See Also: [[Concatenation of Movements| ConcatenationOfMovements]]
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[[Category:Motion Control]]
<!-- [[Category:Motion:PLS]] -->
<!-- [[Category:Motion:HW-PLS]] -->


<!-- @@@@@@@@@@@@@  REMOVED
 After implementing HW assisted PLS new demand came from the application field. The multidimensional PLS. This means switching an output on certain points of a 2 dimensional path (or 3 dimensional). In typical application an XY curve (circle, line or similar) is inscribed on the XY plane where the laser is switched ON/OFF at certain positions. 

The first idea was to implement it analogous to the one-dimensional case so instead of one-dimensional PLS positions we would have PLS multi-dimensional points. This idea was rejected as certain problems raised, problems of detecting when the path enters and when it leaves the point (epsilon sphere) and what is the order of triggering if a list of PLS positions (points) are given. The bottom line is that contrary to the one-dimensional axis PLS, the multidimensional PLS can be entered/exit in many different ways.

Keeping the basic mechanism of PLS, to avoid confusing end-users with a totally new syntax and terminology. The original requirement linked some point in space to a PLS action. There is the disadvantage of non-existing relation between a motion and the PLS. If the path is changed and does not pass through an epsilon environment of the multi-dimensional PLS position, the PLS will not fire anymore and the application logic is totally confusing.

PLSs are linked to motion by a nodal motion parameter which activates the PLS for a certain motion (enabling it nodally for the relevant motion only).
* PLSs linked to a path must be predefined with:
* PLS output
* PLS positions
* PLS motion element type (group instead of axis)
* For each segment of a motion a different PLS can be used (e.g. in first segment switch on laser at starting point, last segment switch off at end point).
* PLS positions have a different meaning 
* Positions cannot be absolute anymore, but must be relative to the motion segment.
* Units are not easy to decide: 
* Percentage
* Differs from the axis PLS
* Easy to be handled in motion
* Ease of use for the end-user depends on ability to calculate offsets to start or end ratio-wise
* User units
* Same as axis PLS
* Doable in motion
* Hard to handle for the end-user, if the motion is curved (CIRCLE, AI, ...)
* Due to application in lasers there must be some immediate error action on PLSs to switch off a dangerous power source linked to the PLS output (safe state).
= Description =
@@@@@@@@@@@ -->