Yaskawa SMC–4000 - Manual (Page 285)

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SMC–4000 User Manual
Vector Mode: Linear and Circular Interpolation Motion
The SMC–4000 allows a long 2-D path consisting of linear and arc segments to be prescribed. Motion
along the path is continuous at the precribed vector speed even at transitions between linear and circular
segments. The SMC–4000 performs all of the complex computations of linear and circular interpolation,
freeing the host PC from this time intensive task.
The coordinated motion mode is similar to the linear interpolation mode. Any pair of two axes may be
selected for coordinated motion consisting of linear and circular segments. In addition, a third axis can be
controlled such that it remains tangent to the motion of the selected pair of axes. Note that only one pair
of axes can be specified for coordinated motion at any given time.
The command VM m,n,p where “m” and “n” are the coordinated pair and “p” is the tangent axis.
NOTE: The commas which separate m,n and p are not necessary. For example, VM XYZ selects the XY
axes for coordinated motion and the Z-axis as the tangent.
Specifying the Coordinate Plane
The SMC–4000 allows for 2 separate sets of coordinated axes for linear interpolation mode or vector
mode. These two sets are identified by the letters S and T.
To specify vector commands the coordinate plane must first be identified. This is done by issuing the
command CAS to identify the S plane or CAT to identify the T plane. All vector commands will be
applied to the active coordinate system until changed with the CA command.
Specifying Vector Segments
The motion segments are described by two commands: VP for linear segments and CR for circular
segments. Once a set of linear segments and/or circular segments have been specified, the sequence is
ended with the command VE. This defines a sequence of commands for coordinated motion.
Immediately prior to the execution of the first coordinated movement, the controller defines the current
position to be zero for all movements in a sequence.
*Note This ‘internal’ definition of zero does not affect the absolute coordinate system or
subsequent coordinated motion sequences.
The command, VP xy specifies the coordinates of the end points of the vector movement with respect to
the starting point. Non-Sequential Axes do not require comma delimitation. The command, CR r,q,d
defines a circular arc with a radius r, starting angle of q, and a traversed angle d. The notation for q is that
zero corresponds to the positive horizontal direction, and for both q and d, the counterclockwise (CCW)
rotation is positive.
Up to 511 segments of CR and VP may be specified in a single sequence and must be ended with the
command VE. The motion can be initiated with a Begin Sequence (BGS) command. Once motion starts,
additional segments may be added.
The Clear Sequence (CS) command can be used to remove previous VP and CR commands which were
stored in the buffer prior to the start of the motion. To stop the motion, use the instructions STS or AB1.
STS stops motion at the specified deceleration. AB1 aborts the motion instantaneously.
The Vector End (VE) command must be used to specify the end of the coordinated motion. This
command tells the controller to decelerate to a stop following the last motion in the sequence. If a VE
command is not given, an Abort (AB1) must be used to abort the coordinated motion sequence.
The user must keep enough motion segments in the SMC–4000 sequence buffer to ensure continuous
motion. If the controller receives no additional motion segments and no VE command, the controller will
stop motion instantly at the last vector. There will be no controlled deceleration. LM? or _LM returns the
available spaces for motion segments that can be sent to the buffer. 511 returned means the buffer is
empty and 511 segments can be sent. A zero means the buffer is full and no additional segments can be
sent. As long as the buffer is not full, additional segments can be sent at the PCI bus speeds.
The operand _CS can be used to determine the value of the segment counter.