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APEX615n Installation Guide
STRGTE
STRGTD
STRGTV
STRGTT
Target Zone Mode Enable
Target Zone Distance
Target Zone Velocity
Target Zone Timeout Period
When using the Target Zone Mode, enabled with the STRGTE command, the actual
position and actual velocity must be within the
target zone
(that is, within the distance zone
defined by STRGTD and within the velocity zone defined by STRGTV). If the motor/load
does not settle into the target zone before the timeout period set by STRGTT, the
APEX615n detects an error.
To prevent subsequent commands/moves from being executed when this error condition
occurs, you must enable the ERROR command to continually check for this error
condition, and when it occurs to branch to a programmed response defined in the ERRORP
program. Otherwise, subsequent commands/moves can be executed regardless of the
actual position and velocity.
This feature is explained in greater detail later in the
Target Zone
section.
TFB and
[ FB ]
Position of Servo Feedback Devices
Transfers [or assigns/compares] the actual position of the transducer selected for
feedback (see SFB).
TDAC and
[ DAC ]
Value of DAC Output
Transfers [or assigns/compares] the output from the APEX615n’s digital-to-analog
converter. This is the analog control signal output to the APEX615n’s internal drive.
TGAIN
Transfer Servo Gains
Transfers the currently active set of PIV&F gains. The servo gain set reported represents
the last gain values specified with the individual servo gain commands (SGI, SGP, SGV,
SGAF, and SGVF), or the last gain set enabled with the SGSET command.
TPC and
[ PC ]
Position Commanded
Transfers [or assigns/compares] the commanded position (intermediate position setpoint).
TPER and
[ PER ]
Position Error
Transfers [or assigns/compares] the error between the commanded position (TPC) and
the actual position (TFB, TPE, or TANI) as measured by the feedback device.
TSGSET
Transfer Servo Gain Set
Transfers a previously-saved set of servo gain parameters. A gain set is saved with the
SGSET command.
TSTLT
Transfer Servo Settling Time
Transfers the time it took the last move to settle within the
target zone
(that is, within the
distance zone defined by STRGTD and within the velocity zone defined by STRGTV). The
Target Zone Mode does not need to be enabled to use this command.
Servo Control Techniques
To ensure that you are tuning your servo system properly, you should understand the tuning
techniques described in this section.
The APEX615n employs a PIV&F servo control algorithm. The control techniques available
in this system are as follows:
P ......... Proportional Feedback (controlled with the SGP command)
I .......... Integral Feedback (controlled with the SGI command)
V ......... Velocity Feedback (controlled with the SGV command)
F ......... Velocity and Acceleration Feedforward (controlled by the SGVF and SGAF commands,
respectively)
The following block diagram shows these control techniques in relation to the servo control
algorithm configuration. The table presents a condensed summary of each control’s effect on
the servo system.
APEX615n Servo Control Algorithm
Velocity Feedforward
(SGVF)
Acceleration Feedforward
(SGAF)
+ +
+
-
+
-
+
+
Servo
Motor
Servo
Drive
-10V
+10V
Digital-to-Analog
Conversion (DAC)
Current
Output
Servo
System
Variable Integral Limit
(set with SGILIM)
Proportional Feedback
(SGP)
Integral Feedback
(SGI)
Velocity Feedback
(SGV)
Position
Feedback
Device
Dither Control
Frequency (SDTFR)
and Amplitude
(SDTAMP)
Analog
Control Signal
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