ElmoMC SimplIQ Software Manual - Manual (Page 166)

SimplIQ Software Manual The Position Reference Generator
MAN-SIMSW (Ver. 1.4)
11-25
A PT motion is initiated by stating:
PT=N
with 1 < N < 1024, and BG.
The PT=N command sets the read pointer of the QP vector to N.
BG
starts the motion.
The QP vector may be written online during a PT motion, as long as no presently-
executing PT elements are programmed.
a. Mode Termination
The PT motion terminates when one of the following occurs:
ƒ
The motor is shut down, either by programming MO=0 or by an exception.
ƒ Another mode of motion is set active; by programming PA=xxx; BG, for example. In
this case, the new motion command executes immediately, without having to
explicitly terminate the PT mode.
ƒ The PT motion manager runs out of data. This occurs when the read pointer reaches
MP[2] and MP[3] is zero. This may also occur in auto-increment mode (CAN
communications only) if the read pointer reaches the write pointer. In that case, the
PT motion is stopped immediately, using the SD deceleration. Note that if the last
programmed PT speed is zero, the PT motion terminates neatly.
b. PVT Motion Using CAN
The PT table allows for the performance of both pre-designed and online motion plans by
writing the QP vector while PT motion is executing. The online motion design ability is
limited by the speed of the communication interface. With an RS-232 ASCII
communication interface, a single QP vector is programmed with the following format:
QP[xx] = xxx,xxx,xxx;
Up to 18 characters may be required to program a single position point. At a
communication rate of 19,200 baud, this may take 9 milliseconds. At a communication
rate of 115,200 baud, this may take 1.8 milliseconds.
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 drive 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.
c. The PT Motion Programming Message
Two positions for the QP vector can be programmed in the eight bytes of a single PDO —
0x300+ID — where ID is the node ID of the drive. Note that before using this PDO, it
must be mapped as follows:
Object dictionary index: 0x2002
Type: RECORD,
two elements
Access: Write only
Structure: Signed32 Position1; Signed32 Position2
PDO mapping: Yes
Value limits No
Default value: Not applicable