Installation guide

Keyword Reference Guide
MN1270 02.2002 87
See Also:
HOME, POS
HTA
Purpose:
Starts the hold to analog mode of motion in which the position of an axis is controlled in order to keep
the value of an analog input channel at the specified value.
Controllers Supported:
NextMove PCI NextMove PC NextMove BX MintDrive ServoNode 51
  
Format:
HTA[axes] = <expression> {,<expression> ...}
v = HTA[axis]
Dot Parameters:
Axis - Axis No.
Attributes:
Controller Read Write Command Multi-
Axis
Scaled Default Range
NextMove
  
0
-100 ≤ x ≤ 100
Description:
Hold To Analog (HTA) is a mode of motion which allows the value seen on one of the analog input
channels to be held at a constant specified value where the position of the axis has a direct affect on the
value seen on the analog channel. The
HTA keyword specifies the desired analog hold value.
The axis position is controlled to minimize the error between the desired hold value and the measured
analog value. The Hold To Analog algorithm uses a proportional gain (
HTAGAIN) and a damping term
(
HTADAMPING) to control motor position. The normal PIDVF loop is also used to control the axis
position.
The axis must be idle and free from errors before the move can be started. Only further HTA moves
can be loaded on the axis to change to current hold value. The move type is subject to all synchronous
and asynchronous error conditions. If an asynchronous error dictates that the
ERRORDECEL must be
used then the move will stop using
ERRORDECEL.
The motion is subject to all NextMove error types.
The motion of the axis is at all times within the profile defined with the
ACCEL, DECEL and
SPEED/FEEDRATE keywords. The response of the axis to an error on the analog channel can therefore
be easily controlled
Reading the keyword returns the current value being held to. If the axis is not currently in
HTA mode,
then reading the keyword will return the last hold value.
The analog channel to use is defined with the
HTACHANNEL keyword. It also possible to set up an
analog filter with the
HTAFILTER keyword and to set up an error deadband with the HTADEADBAND
keyword.
The motion can be terminated by the
STOP keyword which will cause the axis to ramp down at the
current deceleration rate or
CANCEL which will cause the axis to crash stop.
The value passed to the keyword is the desired value to be seen on the analog input channel. The valid
range of the hold value depends on the current configuration of the analog input channel. The analog
input channel is set with the
HTACHANNEL keyword and the analog channel configuration is set with the
ADCMODE keyword.
The
GO keyword is required to start motion. Hold To Analog can be used on servo or stepper axes.
Example:
AXES[2] : REM Use axis 2
ADCMODE.6 = 2 : REM Configure channel 6 to be single ended, bipolar