Reference Manual

16-Axis MACRO CPU Software Reference Manual
40 16-Axis MACRO Station MI-Variable Reference
In any of the quadrature decode modes, PMAC is expecting two input waveforms on CHAn and CHBn,
each with approximately 50% duty cycle, and approximately one-quarter of a cycle out of phase with
each other. “Times-one” (x1) decode provides one count per cycle; x2 provides two counts per cycle; and
x4 provides four counts per cycle. The vast majority of users select x4 decode to get maximum
resolution.
The clockwise (CW) and counterclockwise (CCW) options simply control which direction counts up. If
you get the wrong direction sense, simply change to the other option (e.g. from 7 to 3 or vice versa).
Note:
If you change the direction sense of an encoder with a properly working servo
without also changing the direction sense of the output, you can get destabilizing
positive feedback to your servo and a dangerous runaway condition.
In the pulse-and-direction decode modes, PMAC is expecting the pulse train on CHAn, and the direction
(sign) signal on CHBn. If the signal is unidirectional, the CHBn line can be allowed to pull up to a high
state, or it can be hardwired to a high or low state.
If MI910 is set to 8, the decoder inputs the pulse and direction signal generated by Channel n’s pulse
frequency modulator (PFM) output circuitry. This permits the 16-Axis MACRO Station to create a
phantom closed loop when driving an open-loop stepper system. No jumpers or cables are needed to do
this; the connection is entirely within the ASIC. The counter polarity automatically matches the PFM
output polarity.
If MI910 is set to 12, the timer circuitry is set up to read magnetostrictive linear displacement transducers
(MLDTs) such as Temposonics
TM
. In this mode, the timer is cleared when the PFM circuitry sends out
the excitation pulse to the sensor on PULSEn, and it is latched into the memory-mapped register when the
excitation pulse is received on CHAn.
If MI910 is set to 11 or 15, the channel is set up to accept 3-phase “hall-effect” style inputs on the A, B,
and C inputs, decoding 6 states per cycle.
MS{node},MI911 Position Compare n Channel Select
Range: 0 - 1
Units: None
Default: 0
0: Use channel n encoder counter for position compare function
1: Use first encoder counter on IC (encoder 1 for channels 1 to 4;
encoder 5 for channels 5 to 8) for position compare function
MI911 determines which encoder input that the position compare circuitry for the machine interface
channel mapped to the specified node uses.
When MI911 is set to 0, the channel's position compare register is tied to the channel's own encoder
counter, and the position compare signal appears only on the EQUn output.
When MI911 is set to 1, the channel's position compare register is tied to the first encoder counter on the
ASIC -- Encoder 1 for channels 1-4, Encoder 5 for channels 5-8, or Encoder 9 for channels 9-10 -- and
the position compare signal appears both on EQUn, and combined into the EQU output for the first
channel on the IC (EQU1 or EQU5); executed as a logical OR.
MI911 for the first channel on an ASIC performs no effective function, so is always 1. It cannot be set to
0.