Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Synchronizing Turbo PMAC to External Events
345
SYNCHRONIZING TURBO PMAC TO EXTERNAL EVENTS
Turbo PMAC has several powerful features to help in synchronizing the motion under Turbo PMAC
control to external events. These include –
control to external events. These include –
•
Position following, commonly known as electronic gearing; time-base control, commonly known as
electronic cams
electronic cams
•
Position capture, which is useful for registration applications
•
Position compare, which can be used for precision scanning and measurement applications.
Each of these areas is covered below.
Position Following (Electronic Gearing)
Turbo PMAC has several methods of coordinating the axes under its control with axes not under its
control. The simplest method is basic position following. This is a motor-by-motor function, not a
coordinate system function as time-base following is (see below). An encoder signal from the master axis
(which is not under Turbo PMAC’s control) is fed into one of Turbo PMAC’s encoder inputs. Typically,
this master signal is from either an open-loop drive or a handwheel knob.
control. The simplest method is basic position following. This is a motor-by-motor function, not a
coordinate system function as time-base following is (see below). An encoder signal from the master axis
(which is not under Turbo PMAC’s control) is fed into one of Turbo PMAC’s encoder inputs. Typically,
this master signal is from either an open-loop drive or a handwheel knob.
Position Following I-Variables
One or more of Turbo PMAC’s motors is told that this encoder register is the master (with Ixx05). Ixx05
is an address I-variable; that is, its value contains the address of the register holding the master position
information. Typically, this register is that of some processed position data in the Encoder Conversion
Table. It is helpful to have done the 1/T or similar to reduce the quantization noise in the sampling of the
master encoder (this is done automatically in the default setup).
is an address I-variable; that is, its value contains the address of the register holding the master position
information. Typically, this register is that of some processed position data in the Encoder Conversion
Table. It is helpful to have done the 1/T or similar to reduce the quantization noise in the sampling of the
master encoder (this is done automatically in the default setup).
Encoder Table
$0720-$0739
Ix07
Ix05
D
+
-
PI
FE
CP
AP
Ix05 Master (HW) Position Address & Mode
Ix06 Following Enable
Ix07 Master Scale Factor
Ix08 Position Loop (Load) Scale Factor
Ix09 Velocity Loop (Motor) Scale Factor
Ix06 Following Enable
Ix07 Master Scale Factor
Ix08 Position Loop (Load) Scale Factor
Ix09 Velocity Loop (Motor) Scale Factor
+
-
HW
Ix06
+
Ix08
Ix09
Ix08
Trajectory
Command
Cannot be
changed on
the fly
To DAC
Actual
Motor
Position
Actual
Load
Position
Can be
changed on
the fly
POSITION FOLLOWING PARAMETERS
The following ratio for each motor is set by Ixx07 and Ixx08, which can be analogized to the number of
gear teeth on master and slave, or the radii of the belted wheels, in a mechanical following application.
The following function is turned on and off with bit 0 of Ixx06. When it is on, the input stream from the
master acts just like a trajectory generator, creating a series of commanded positions to which the
following axis controls.
gear teeth on master and slave, or the radii of the belted wheels, in a mechanical following application.
The following function is turned on and off with bit 0 of Ixx06. When it is on, the input stream from the
master acts just like a trajectory generator, creating a series of commanded positions to which the
following axis controls.