A contour is described by position increments which are described with the command, CD x,y,z,w over a time
interval, DT n. The parameter, n, specifies the time interval. The time interval is defined as 2
n
sample period (1 ms
for TM1000), where n is a number between 1 and 8. The controller performs linear interpolation between the
specified increments, where one point is generated for each sample. If the time interval changes for each segment,
use CD x,y,z,w=n where n is the new DT value.
Consider, for example, the trajectory shown in Figure 6.18. The position X may be described by the points:
Point 1
X=0 at T=0ms
Point 2
X=48 at T=4ms
Point 3
X=288 at T=12ms
Point 4
X=336 at T=28ms
The same trajectory may be represented by the increments
Increment 1
DX=48
Time=4
DT=2
Increment 2
DX=240
Time=8
DT=3
Increment 3
DX=48
Time=16
DT=4
When the controller receives the command to generate a trajectory along these points, it interpolates linearly
between the points. The resulting interpolated points include the position 12 at 1 msec, position 24 at 2 msec, etc.
The programmed commands to specify the above example are:
#A
CMX
Specifies X axis for contour mode
CD 48=2
Specifies first position increment and time interval, 2
2
ms
CD 240=3
Specifies second position increment and time interval, 2
3
ms
CD 48=4
Specifies the third position increment and time interval, 2
4
ms
CD 0=0
End Contour buffer
#Wait;JP#Wait,_CM<>511
Wait until path is done
EN
Figure 6.18: The Required Trajectory
Additional Information
_CM gives the amount of space available in the contour buffer (511 maximum). Zero parameters for DT followed
by zero parameters for CD will exit the contour mode.
If no new data record is found and the controller is still in the contour mode, the controller waits for new data. No
new motion commands are generated while waiting. If bad data is received, the controller responds with a ?.
Specifying a -1 for the DT or as the time interval in the CD command will pause the contour buffer.
Issuing the CM command will clear the contour buffer.
Chapter 6 Programming Motion ▫ 101
DMC-40x0 User Manual
POSITION
(COUNTS)
240
96
48
192
TIME (ms)
0
4
8
12
16
20
24
28
288
336
SEGMENT 1
SEGMENT 2
SEGMENT 3