ADLINK PCI-8164 - Manual (Page 85)

Operation Theory 73
The StrVel and MaxVel parameters are given in units of pulses per
second (PPS). The Tacc and Tdec parameters are in units of sec-
ond to represent accel./decel. time respectively. You must know
the physical meaning of “one pulse” to calculate the physical value
of the relative velocity or acceleration parameters. The following
formula gives the basic relationship between these parameters:
X MaxVel = StrVel + accel*Tacc;
X StrVel = MaxVel + decel *Tdec;
Where accel/decel represents the acceleration/deceleration rate in
units of pps/sec^2. The area inside the trapezoidal profile repre-
sents the moving distance.
Units of velocity setting are pulses per second (PPS). Usually,
units of velocity of the manual of motor or driver are in rounds per
minute (RPM). A simple conversion is necessary to match
between these two units. Here we use an example to illustrate the
conversion:
A servomotor with an AB phase encoder is used in a X-Y table.
The resolution of encoder is 2000 counts per phase. The maxi-
mum rotating speed of motor is designed to be 3600 RPM. What is
the maximum pulse command output frequency that you have to
set on 8164?
Answer: MaxVel = 3600/60*2000*4 = 480000 PPS
Multiplying by 4 is necessary because there are four states per AB
phase (See Section 4.4).
Usually, the axes need to set the move ratio if their mechanical
resolution is different from the resolution of command pulse. For
example, if an incremental encoder is mounted on the working
table to measure the actual position of moving part. A servomotor
is used to drive the moving part through a gear mechanism. The
gear mechanism is used to convert the rotating motion of the
motor into linear motion (see the following diagram). If the resolu-
tion of the motor is 8000 pulses/round, then the resolution of the
gear mechanism is 100 mm/round (i.e., part moves 100 mm if the
motor turns one round). Then, the resolution of the command
pulse will be 80 pulses/mm. If the resolution of the encoder mount-
ing on the table is 200 pulses/mm, then you have to set the move