ADLINK PCI-8134A - Manual (Page 45)

Operations
• 35
The following diagram shows the trapezoidal profile. There are 9 relative
functions. In the a_move(),
ta_move() and start_a_move(),
start_ta_move() functions, the absolute target position must be given in
the unit of pulse. The physical length or angle of one movement is
dependent on the motor driver and the mechanism (includes the motor).
Since absolute move mode needs the information of current actual position,
so “External encoder feedback (EA, EB pins)” must be enabled in
set_cnt_src() function. And the ratio between command pulses and
external feedback pulse input must be appropriately set by
set_move_ratio() function.
In the r_move(), t_move() and start_r_move(), start_t_move() functions,
the relative displacement must be given in the unit of pulse. Unsymmetrical
trapezoidal velocity profile (Tacc is not equal Tdec) can be specified in
ta_move() and t_move() functions; where symmetrical profile (Tacc = Tdec)
can be specified in a_move() and r_move() functions
The str_vel and max_vel parameters are given in the unit of pulse per
second (pps). The Tacc and Tdec parameters are given in the unit of
second represent accel./decel. time respectively. You have to know the
physical meaning of “one movement” to calculate the physical value of the
relative velocity or acceleration parameters. The following formula gives the
basic relationship between these parameters.
max_vel = str_vel + accel*Tacc;
str_vel = max_vel + decel *Tdec;
where accel/decel represents the acceleration/deceleration rate in unit of
pps/sec. The area inside the trapezoidal profile represents the moving
distance.
The unit of velocity setting is pulses per second (pps). Usually, the unit of
velocity in the manual of motor or driver is in rounds per minute (rpm). A
simple conversion is necessary to match between these two units. Here we
use a example to illustrate the conversion.
For example:
A servo motor with a AB phase encoder is used for a X-Y table. The
resolution of encoder is 2000 counts per phase. The maximum rotating
speed of motor is designed to be 3600 rpm. What is the maximum pulse
command output frequency that you have to set on PCI-8134/PCI-8134A?