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Parameters to Set Up Per-Channel Hardware Signals
For each machine interface channel n (n = 1 to 8) used for sine wave analog
outputs, a few I-variables must be set up properly.
Encoder Decode Control: I9n0
I9n0 must be set up to decode the commutation encoder properly. Almost
always a value of 3 or 7 is used to provide times-4 decode of a quadrature
encoder (4 counts per encoder line). The difference between 3 and 7 is the
direction sense of the encoder; you should set this variable so your motor counts
up in the direction you want.
The polarity sense of the Ix72 commutation phase angle parameter must match
that of I9n0 for your particular wiring; if it is wrong, you will lock into a
position rather than generate continuous torque. A test for determining this
polarity match is given below. Remember that if you change I9n0 on a working
motor, you will have to change Ix72 as well.
Output Mode Control: I9n6
I9n6 must be set to 1 or 3 to specify that outputs A and B for Channel n are in
DAC mode, not PWM. A setting of 1 puts output C (not used for servo or
commutation tasks in this mode) in PWM mode; a setting of 3 puts output C in
PFM mode.
Output Inversion Control: I9n7
I9n7 controls whether the serial data streams to the DACs on Channel n are
inverted or not. The default value of 0 (non-inverted) is suitable for use with the
recommended ACC-8E analog interface board. Inverting the bits of the serial
data stream has the effect of negating the DAC voltage. In a commutation
algorithm this is equivalent to a 180o phase shift, which would produce runaway
if the system were working properly before the inversion.
Parameters to Set Up Motor Operation
Several I-variables must be set up for each Motor x to enable and configure the
sine-wave output for that motor. Of course, Ix00 must be set to 1 for any active
motor, regardless of the output mode for that motor.
Commutation Enable: Ix01
Ix01 is set to 1 to activate the commutation algorithms for Motor x.
PMAC2 User’s Manual – 15 March 1997
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