User's Manual

PMAC User Manual
Setting Up a Motor 77
This table can be used unchanged by the great majority of PMAC users. Note that the default motor
feedback-position-address and master-position-address I-variables (I103-I105, I203-205, etc.) point to
locations in this table and assume the default setup of the table.
However, there are several reasons to change the table:
1. If the application uses an Acc-24 axis expansion board, it will need to convert Encoders 9-16, so
entries for these must be added to the table.
2. If using an external time-base frequency source, the scaling factor and maybe the source should be
changed.
3. If using 1/T interpolation on the position feedback.
4. If requiring fast control on just a few axes, reduce the table to save computation time, because each
conversion does take a finite amount of time.
Example
When using two axes of fast laser-interferometer quadrature feedback (into Encoders 1 and 3) with
parallel sub-count interpolation, and no handwheels or external time base, set up a table as follows for
minimum conversion time:
Minimum Conversion Time Table
Address Y-Word Meaning
$720 (1824) $80C000 || sub-count conversion of Enc. 1
$721 (1825) $80C008 || sub-count conversion of Enc. 3
$722 (1826) $000000 Signifies end-of table
Example
To convert two 16-bit absolute encoders from the first Acc-14 filtered not to allow more than eight bits
change per servo cycle, four incremental encoders (ENC1-4) with 1/T interpolation, four A/D converters
(ADC1-4), and two linear displacement transducers (ENC9-10 timers) without filtering.
The conversion table setup would be:
Two 16-Bit Absolute Encoders Conversion Table
Address Y-Word Meaning
$720 (1824) $00C000 1/T conversion of Encoder 1
$721 (1825) $00C004 1/T conversion of Encoder 2
$722 (1826) $00C008 1/T conversion of Encoder 3
$723 (1827) $00C00C 1/T conversion of Encoder 4
$724 (1828) $10C006 Conversion of ADC1
$725 (1829) $10C007 Conversion of ADC2
$726 (1830) $10C00E Conversion of ADC3
$727 (1831) $10C00F Conversion of ADC4
$728 (1832) $30FFD0 Filtered Parallel from 1st Acc-14
$729 (1833) $00FFFF Use the low 16 bits of word
$72A (1834) $000100 Max change 256 counts/cycle
$72B (1835) $30FFD1 Filtered Parallel from 1st Acc-14
$72C (1836) $00FFFF Use the low 16 bits of word
$72D (1837) $000100 Max change 256 counts/cycle
$72E (1838) $20C020 Parallel from ENC 9 timer
$72F (1839) $07FFFF Use low 19 bits (max allowed)
$730 (1840) $20C024 Parallel from ENC 10 timer
$731 (1841) $07FFFF Use low 19 bits (max allowed)
$732 (1842) $000000 Signifies end-of-table