Elmo HARSFEN0602, HARmonica 133, 12.1.2Comparison of the PT and the PVT interpolated modes

ElmoHARSFEN0602HARmonicaSoftwareManual PRELIMINARYDRAFT

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is . Care must be taken if the smooth factor (SF) is nonzero. Upon switching from interpolated motion to PTP or jogging, the PTP or the Jogging will start un-smoothed. Smoothing will gradually build up. After SF milliseconds, the motion shall be fully smoothed.

Care is required, however, when switching to the tabulated (PT and PVT) motion modes. The PV and the PT modes should be started only when the motor is in complete stop (MS=0 or MS=1), at the exact position specified as the first point for the PT or for the PVT. If the motor is not in complete stop at the correct starting position, the software reference shall jump. The command to the position controller will try to catch up with the PT or the PVT motion, using the SD acceleration – refer the section on "Stop management".

12.1.2Comparison of the PT and the PVT interpolated modes

The following tables compare the PT and the PVT motion modes.

Feature	PT		PVT
Motion buffer length	1024		64
Position points in one CAN	2		1
message
Speed command calculation	Automatic, by 3rd order		Specified by user
	interpolation
Acceleration command	Automatic, by 3rd order		Automatic, by 3rd order
	interpolation		interpolation
Time between user data points	A fixed multiple of the 1 to 255		Specified by the user
	sampling times of the controller.		independently for each motion
	Cannot be changed on the fly.		interval, in msec. In the range
			[1,255] msec.
Cyclical motion support	Yes		Yes
On the fly motion	Yes		Yes
programming with hand-
shaking host protocol
Table 12-2 – Tabulated Motion Difference
Feature		Preferred
Long pre-programmed motions		PT
Ease of use		PT
Variable command sampling time		PVT
Motion design independent of controller sampling		PVT
time
Synchronized, multiple axis motions		PVT

Table 12-3 – Tabulated Feature Preference

12.1.3The Idle Mode and Motion Status

After motor on, the position profiler is Idle. This means that the software position command is fixed. The idle mode is revisited whenever a mode terminates (A PTP or a tabulated motion is completed), or by a stop (ST) command.

The Idle mode is the only mode in which it is possible to change the parameters of the external reference generator.

The Idle mode of the position reference generator may be identified by the MS (Motion Status) variable. The reading of the MS variable are summarized in the following table: