SMAC
LAC-26 Technical Reference Manual
4/29/2013 17
Command:
aPHn
-- Set Servo Phasing --
Argument:
0 <= n <= 63
Default:
0
This command is used to set the output polarity, encoder phasing, Index input sense, Home input
sense, Limit+ and Limit- input sense for servo axis ‘a’. The polarity of the output will determine whether
the servo is driven in a direction that reduces or increases position error. The encoder phase will
determine whether the position count will increase or decrease for a valid encoder input sequence. The
Index sense determines what logic edge will cause the Index input to be active. The Limit+, Limit- and
Home sense determines whether these signals are active “on” or active “off.
To determine the argument to be used with the PH command, use the follow table and add the
required values together.
Add to 'n'
Output Phase Normal
0
Output Phase Reversed
1
Encoder Phase Normal
0
Encoder Phase Reversed
2
Index Active Level Low
0
Index Active Level High
4
Home Sense Active "ON"
0
Home Sense Active "OFF"
8
Limit+ Sense Active "ON"
0
Limit+
Sense
Active
16
"OFF"
Limit- Sense Active "ON"
0
Limit- Sense Active "OFF"
32
For example, if it were necessary to reverse the encoder phasing and to set the Limit+ and Limit-
inputs to active "OFF", then 'n' would be (2 + 16 + 32) or 50. The default phasing and sense is equivalent
to issuing this command with a argument of 0.
Command:
aRIn
-- Sampling Rate of Integral --
Argument:
0 <= n <= 127
Default:
0
This command allows for the adjustment of the PID digital filter integral sampling interval for servo
axis 'a'. The period of this interval can be calculated by the following:
T = (n+1) * S * 0.000100
where "T" is the period in seconds, "n" is the RI command argument and "S" is the sample period count
specified by the Servo Speed (SS) command. For example, if the value previously set by the SS
command is 10 and the value set by the RI command is 1, then the integral sample period will be:
(1+1) * 10 * 0.000100 = .002000 S or 2 mS
This command is useful in tuning the PID servo loop to the inertial properties of the system.
Related Commands: FR
