ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 238)

Command Mode
ST
Idle: ST stops any motion.
PA PTP: PA=n specifies a PTP motion, to absolute position n counts.
JV Jog: JV=n specifies a jog motion, at speed n counts/second.
PT PT: PT=n specifies a PT motion, beginning from the nth item in the
PT data table.
PV PVT: PV=n specifies a PVT motion, beginning from the nth item in
the PVT data table.
Table 6-1: Software Motion Mode Commands
6.1.1 Switching Between Motion Modes
The ST command can be used for stopping at any time. The drive will decelerate the
position or velocity reference until it reaches a full stop.
PTP and jog motion commands can be sent anywhere, at any time. The drive will calculate
the path to be followed so that the desired speed or position is reached, subject to the
acceleration limits. PTP and jog motions can even be initiated during PVT or PT motion.
Care must be taken, however, if the smooth factor (SF) is nonzero. Upon switching from
interpolated motion to PTP or jogging, the PTP or jogging will start unsmoothed, with
smoothing gradually building up, until after SF milliseconds, the motion is fully smoothed.
Care is also required when switching to tabulated (PT and PVT) motion modes. These
modes should be started only when the motor is at a complete stop (MS=0 or MS=1), at the
exact position specified as the first point for the PT or PVT. If the motor is not totally
stopped at the correct start position, the software reference will jump. The command to the
position controller will attempt to catch up with the PT or PVT motion, using the SD
acceleration.
6.1.2 Comparing PT and PVT Interpolated Modes
The following tables compare PT and PVT motion modes.
Feature PT PVT
Motion buffer length
1024 64
Position points in one
CAN message 2 1
Speed command
calculation Automatic, by
interpolation Specified by user
Acceleration command Automatic, by
interpolation Automatic, by
interpolation
Time between user data
points Fixed multiple of the
1 - 255 controller
sampling times. Cannot
be changed on-the-fly. Specified by user
independently for each
motion interval, in msec.
Range: [1…255] msec.
Cyclical motion support Yes Yes
SimplIQ for Steppers Application Note The Position Reference Generator
MAN-STECR (Ver. 1.1)
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