Reference Manual

PMAC 2 Software Reference
142 PMAC I-Variable Specifiation
I9n2 Encoder n Capture Control {PMAC2 only}
Range
0 .. 15
Units
none
Default
1
Remarks
This parameter determines which input signal or combination of signals for channel n, and
which polarity, triggers a hardware position capture of the counter for encoder n. If a flag
input (home, limit, or user) is used, I9n3 determines which flag. Proper setup of this
variable is essential for a successful home search, which depends on the position-capture
function. The following settings may be used:
Setting Meaning
0 Software Control (immediate capture)
1 Rising edge of CHCn (third channel)
2 Rising edge of Flag n (as set by Flag Select)
3 Rising edge of [CHCn AND Flag n] – Low true index, high true Flag
4 Software Control (immediate capture)
5 Falling edge of CHCn (third channel)
6 Rising edge of Flag n (as set by Flag Select)
7 Rising edge of [CHCn/ AND Flag n] – Low true index, high true Flag
8 Software Control (immediate capture)
9 Rising edge of CHCn (third channel)
10 Falling edge of Flag n (as set by Flag Select)
11 Rising edge of [CHCn AND Flag n/] – High true index, low true Flag
12 Software Control (immediate capture)
13 Falling edge of CHCn (third channel)
14 Falling edge of Flag n (as set by Flag Select)
15 Rising edge of [CHCn/ AND Flag n/] – Low true index, low true Flag
Note that 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, Ix25 must use flags of the same channel
number as the encoder that Ix03 uses for position-loop feedback.
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).
The trigger is armed when the position capture register is read. After this, as soon as
PMAC2 sees that the specified input lines are in the specified states, the trigger will occur
– it is level-triggered, not edge-triggered.