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USER MANUAL Chapter 6 Programming Motion • 75
Changing Feedrate:
The command VR n allows the feedrate, VS, to be scaled between 0 and 10 with a resolution of .0001.
This command takes effect immediately and causes VS scaled. VR also applies when the vector speed
is specified with the ‘<’ operator. This is a useful feature for feedrate override. VR does not ratio the
accelerations. For example, VR .5 results in the specification VS 2000 to be divided By two
Compensating for Differences in Encoder Resolution:
By default, the DMC-13X8 uses a scale factor of 1:1 for the encoder resolution when used in vector
mode. If this is not the case, the command, ES can be used to scale the encoder counts. The ES
command accepts two arguments which represent the number of counts for the two encoders used for
vector motion. The smaller ratio of the two numbers will be multiplied by the higher resolution
encoder. For more information, see ES command in Chapter 11, Command Summary.
Trippoints:
The AV n command is the After Vector trippoint, which waits for the vector relative distance of n to
occur before executing the next command in a program.
Tangent Motion:
Several applications, such as cutting, require a third axis (i.e. a knife blade), to remain tangent to the
coordinated motion path. To handle these applications, the DMC-13X8 allows one axis to be specified
as the tangent axis. The VM command provides parameter specifications for describing the
coordinated axes and the tangent axis.
VM m,n,p
m,n specifies coordinated axes p specifies tangent axis such as X,Y,Z,W p=N
turns off tangent axis
Before the tangent mode can operate, it is necessary to assign an axis via the VM command and define
its offset and scale factor via the TN m,n command. m defines the scale factor in counts/degree and n
defines the tangent position that equals zero degrees in the coordinated motion plane. The operand
_TN can be used to return the initial position of the tangent axis.
Example:
Assume an XY table with the Z-axis controlling a knife. The Z-axis has a 2000 quad counts/rev
encoder and has been initialized after power-up to point the knife in the +Y direction. A 180
° circular
cut is desired, with a radius of 3000, center at the origin and a starting point at (3000,0). The motion is
CCW, ending at (-3000,0). Note that the 0
° position in the XY plane is in the +X direction. This
corresponds to the position -500 in the Z-axis, and defines the offset. The motion has two parts. First,
X,Y and Z are driven to the starting point, and later, the cut is performed. Assume that the knife is
engaged with output bit 0.
#EXAMPLE Example program
VM XYZ XY coordinate with Z as tangent
TN 2000/360,-500 2000/360 counts/degree, position -500 is 0 degrees in XY plane
CR 3000,0,180 3000 count radius, start at 0 and go to 180 CCW
VE End vector
CB0 Disengage knife
PA 3000,0,_TN Move X and Y to starting position, move Z to initial tangent position
BG XYZ Start the move to get into position
AM XYZ When the move is complete
SB0 Engage knife
WT50 Wait 50 msec for the knife to engage