PMAC/PMAC2 V1.17C Addendum MLDT Timer Entries The second line in an MLDT entry should be $07FFFFF to specify the use of the low 19 bits. The third line in an MLDT entry should contain a number slightly greater than the maximum velocity ever expected, expressed as timer increments per servo cycle. An increment of the 120 MHz timer represents about 0.024mm (0.0009 in) on a typical MLDT device. This value represents the maximum change in position reading that will be passed through the conversion table in a single servo cycle, and it provides an important protection against missing or spurious echo pulses. Word-Wide Parallel Feedback :
The ACC-14D and 14V boards are often used to connect parallel data from an absolute encoder or interferometer. The following table shows the entry first lines for the registers on these boards. The latched input registers on ACC-14D/V boards are mapped into Y-registers and filtering is usually desired, so a $3 method digit is used. In most cases, the normal shift is applied, making the second digit $0, but if the feedback has very high resolution, as can happen with an interferometer, the second digit should be set to $8 to disable shifting. ACC-14D/V Port Entries x = 0: normal shift; x = 8: no shift Byte-Wide Parallel Feedback :
The ACC-14P is a PCI-format board that can be used to connect parallel data from an absolute encoder or interferometer. The following table shows the entry first lines for the registers on these boards. The latched input registers on ACC- 14D/V boards are mapped into Y-registers and filtering is usually desired, so a $3 method digit is used. The data is byte-wide, so bit 18 (value of 4 in the second digit) is set to 1. Ports A and B occupy the low bytes of each word, so bits 16 and 17 get a combined value of 1, making the second hex digit $5. Ports C and D occupy the middle bytes of each word, so bits 16 and 17 get a combined value of 2, making the second hex digit $6.
If no shifting of the result data is desired, bit 19 (value of 8 in this digit) is also set to 1, making the second hex digit $D or $E Ports A and C on these boards start in the board’s base address; Ports B and D start in {Base+3}. 18 V1.17C Firmware Version Channel Entry Channel Entry Channel Entry Channel Entry 1 $30C000 5 $30C020 9 $30C040 13 $30C060 2 $30C008 6 $30C028 10 $30C048 14 $30C068 3 $30C010 7 $30C030 11 $30C050 15 $30C070 4 $30C018 8 $30C038 12 $30C058 16 $30C078 ACC 14 # Port Entry ACC 14 # Port Entry 1 A $3xFFD0 4 A $3xFFE8 1 B $3xFFD1 4 B $3xFFE9 2 A $3xFFD8 5 A $3xFFF0 2 B $3xFFD9 5 B $3xFFF1 3 A $3xFFE0 6 A $3xFFF8 3 B $3xFFE1 6 B $3xFFF9