Elmo HARmonica, HARSFEN0602 software manual 156, PT Motion Using can, PT Motion Programming Message

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BG starts the motion.

The QP vector may be written on-line while a PT motion is on, as long as you don't program presently executing PT elements.

12.1.7.5Mode Termination

The PT motion terminates upon one of the following cases:

The motor is shut down, either by programming MO=0 or by an exception.

Another mode motion is set active, e.g. by programming PA=xxx;BG. In this case the new motion

•command executes immediately, without having to explicitly terminate the PT mode.

The PT motion manager runs out of data. This happens when the read pointer reaches MP[2] and MP[3] is zero. This may also happen in the auto increment mode (CAN communications only, see below) if the read pointer reaches the write pointer. Then the PT motion is stopped immediately, using the SD deceleration. Note that if the last programmed PT speed is zero, then the PT motion terminates neatly.

12.1.7.6PT Motion Using CAN

The PT table allows the performance of pre-designed motion plans, as well as the on-line design of motion plans by writing the QP vector while PT motion is executing.

The on-line motion design ability is limited by the speed of communication interface. Consider an RS-232 ASCII communication interface.

Programming of a single QP vector element has the format QP[xx]=xxxxxxxxx;

Up to 18 characters may be required to program a single position point.

At the communication rate of 19200 baud, this may take 9msec, and 1.8msec at the baud rate of 115200.

The CAN communication option allows much faster PT programming, by packing two position points into one PDO communication packet. For easy synchronization with the host, the Amplifier may be programmed to send the PT read and write pointers continuously to the host as a synchronous PDO, or to send an emergency object whenever the number of yet unexecuted motion segments falls below a given threshold.

12.1.7.7The PT Motion Programming Message

Two positions for the QP vector can be programmed in the eight bytes of a single PDO.

The PDO used is 0x300+ID where ID is the node ID of the Amplifier. Note that before using PDO 0x300+ID for PT, its PDO mapping must be first set correctly.

The mapping of this PDO for the PT mode is listed in the table below.

Object Dictionary Index	0x2002
Type	RECORD, 2 elements
Access	Write only
Structure:	Signed32 Position1
	Signed32 Position2
PDO mapping	Yes
Value limits	No
Default value	Not Applicable

Note that the PDO does not specify the QP vector elements to be programmed. The elements to be programmed are specified by a “write pointer”.

The value of the write pointer may be set by the parameter MP[6].

The value of the write pointer may be set once for the entire motion. The write pointer is incremented automatically by two each time the amplifier receives a new PT motion-programming message.

The CAN auto increment mode has the following flow diagram:

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