Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 137
WARNING:
An unreliable phasing search method can lead to a runaway condition. Test the
phasing search method carefully to make sure it works properly under all
conceivable conditions. Make sure the Ixx11 fatal following error limit is active
and as tight as possible so the motor will be killed quickly in the event of a serious
phasing search error.
Phasing search move method: The two-guess phasing search is very quick and requires little
movement, but can be adversely affected if there are significant external loads such as friction and
gravity. The stepper-motor phasing search takes more time and causes more movement, but it is more
reliable in the presence of significant external loads.
Absolute motor position read: If Ixx10 is set to 0, the position reference for a motor comes from a
homing search move. If Ixx10 is greater than 0, the position reference comes from reading an absolute
position sensor at the address specified by Ixx10 and with the format specified by Ixx95. In this case,
Ixx80 bit 2 specifies whether this read is done automatically at power-up/reset.
If the absolute position read is not done automatically at power-up/reset, the motor position will be set to
0 at this time. This does not prevent full operation of the motor. The $* or $$* command must be used
later to read the sensor and establish absolute position. Even if the absolute position is read automatically
at power-up/reset, it may be read again later with the $* or $$* command.
See Also:
Power-Up Phasing Search (Setting Up PMAC Commutation)
On-line commands $, $$, $* $$*, $$$
I-Variables Ixx01, Ixx73, Ixx74, Ixx78, Ixx81
Ixx81 Motor xx Power-On Phase Position Address
Range: $000000 - $FFFFFF
Units: Turbo PMAC or multiplexer-port addresses
Default: 0
WARNING:
An unreliable phasing reference method can lead to a runaway condition. Test the
phasing reference method carefully to make sure it works properly under all
conceivable conditions. Make sure the Ixx11 fatal following error limit is active
and as tight as possible so the motor will be killed quickly in the event of a serious
phasing search error.
Ixx81 tells Turbo PMAC what address to read for absolute power-on phase-position information for
Motor xx, if such information is present. This can be a different address from that of the ongoing phase
position information, which is specified by Ixx83, but it must have the same resolution and direction
sense. Ixx81 is set to zero if no special power-on phase position reading is desired, as is the case for an
incremental encoder.
If Ixx81 is set to zero, a power-on phasing search routine is required for synchronous fixed-field brushless
motors (permanent magnet, and switched reluctance); those that have a slip gain (Ixx78) of zero. Turbo
PMAC’s automatic phasing search routines based on Ixx73 and Ixx74 can be used, or a custom power-on
PLC routine can be written.
Note:
Ixx81 is used for PMAC’s commutation algorithms alone, to locate position within
one electrical cycle of the motor. It is not used for any servo loop position
information, even for power-up. Ixx10 and Ixx95 are used for that purpose.