Parker ViX250CM, User Manual

Page: 71 / 220

4. CONTROL OF VIX DRIVES 63
PA Description
PA reports the actual position of the motor shaft, assuming a primary encoder is fitted.
Although PA is marked as being read only it will accept the value 0 to be written to it for
resetting purposes. If you perform a W(PA,0) system variables PF, PE and PT will also be
set to 0.
PE Description
PE reports the position error, that is, the difference between PT and PA.
PF Description
PF reports the position fed-back by a remotely mounted encoder for following applications.
This is the position demanded by the following input. Counts are only recorded when
following is enabled and at the scaled rate, this means if the scale is -50% and 4000 counts
are received by the drive, PF will read –2000.
PI Description
PI reports the distance moved by the last move (G) command.
PM Description
PM reports the number of counts received from power-on by the following input. No scaling
is applied and PM counts regardless of following being on or off. Writing a number to PM
sets the modulus for count wrapping. That is, writing a specific number of counts to PM sets
the count required before the drive re-starts counting from zero again. This is useful if you
wish to know the position of the motor shaft as an arbitrary count.
For example writing a count of 4000 to PM means that for every shaft rotation a new count of
0 to 3999 is started (until the absolute count limit is reached). By reading PM, a count will be
returned that is somewhere between 0 and 3999, the exact value being an indication of the
instantaneous shaft position.
PR Position Registration Description
PR always reports the position of the motor from the primary feedback (X2 connector) signal
on the last active transition on user input 2. The signal is only active at the start of a valid
REG move.
PS Position Secondary Description
PS reports the position of the following input from the secondary feedback (X4 connector)
signal on the last active transition on user input 1.
PT Description
PT reports the open loop target position of the motor, that is, where you have commanded
the motor to move to.
RB Description
Reports the state of the controller as being ready or busy. While executing a program or
subroutine the controller is busy.