Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 229
 I7mn2 = 3: Capture on (Index high AND Flag n high)
 I7mn2 = 4: Software control – triggered
 I7mn2 = 5: Capture on Index (CHCn) low
 I7mn2 = 6: Capture on Flag n high
 I7mn2 = 7: Capture on (Index low AND Flag n high)
 I7mn2 = 8: Software control – armed
 I7mn2 = 9: Capture on Index (CHCn) high
 I7mn2 = 10: Capture on Flag n low
 I7mn2 = 11: Capture on (Index high AND Flag n low)
 I7mn2 = 12: Software control – triggered
 I7mn2 = 13: Capture on Index (CHCn) low
 I7mn2 = 14: Capture on Flag n low
 I7mn2 = 15: Capture on (Index low AND Flag n low)
Only flags and index inputs of the same channel number as the encoder may be used for hardware capture
of that encoder’s position. This means that to use the hardware capture feature for the homing search
move, Ixx25 must use flags of the same channel number as the encoder that Ixx03 uses for position-loop
feedback.
The trigger is armed when the position capture register is read. After this, as soon as the Servo IC
hardware sees that the specified input lines change into the specified states, the trigger will occur -- it is
edge-triggered, not level-triggered.
Note:
Several of these values are redundant. To do a software-controlled position
capture, preset this parameter to 0 or 8; when the parameter is then changed to 4 or
12, the capture is triggered (this is not of much practical use, but can be valuable
for testing the capture function).
I7mn3 Servo IC m Channel n Capture Flag Select Control
Range: 0 - 3
Units: none
Default: 0
I7mn3 determines which of the Flag inputs will be used for hardware position capture (if one is used) of
the encoder counter of Channel n on PMAC-style Servo IC m. I7mn2 determines whether a flag is used
and which polarity of the flag will cause the trigger. The possible values of I7mn3 and the flag each
selects is:
 I7mn3 = 0: HMFLn (Home Flag n)
 I7mn3 = 1: -LIMn (Positive End Limit Flag n)
 I7mn3 = 2: +LIMn (Negative End Limit Flag n)
 I7mn3 = 3: FAULTn (Amplifier Fault Flag n)
Typically, I7mn3 is set to 0 for homing search moves in order to use the home flag for the channel. To
capture on the -LIMn or +LIMn overtravel limit flags or the FAULTn amplifier fault flag, disable their
normal functions with Ixx25 or use a channel n where none of the flags is used for the normal axis
functions.
Note:
The direction sense of the limit inputs is the opposite of what many people
consider intuitive. That is, the +LIMn input, when taken high (opened), stops
commanded motion in the negative direction; the -LIMn input, when taken high,
stops commanded motion in the positive direction. It is important to confirm the
direction sense of the limit inputs in actual operation.