Accessory 24E2S
MLDT Feedback for UMAC-Turbo & UMAC-MACRO
31
MS{anynode},MI904/MI908 (PFM Pulse Width)
The pulse width, set by MI904/MI908 in units of PFM clock cycles must be set long enough for the MLDT
to see, and long enough to contain the rising edge of the RPM start echo pulse, or the rising edge of the
single DPM echo pulse. For example, if this edge can come up to 2
sec after the start of the excitation
pulse, and the PMAC clock cycle is at its default of about 0.1
sec, then I7m04 must be set at least to 20.
MS{node},MI916 (Output Format Select)
For the channel associated with this node to be used for MLDT feedback, MI916 must be set to 1 or 3 for
the C sub-channel to be used for PFM-format output. On an Acc-24E2A, I7mn6 must then be set to 3 for
the A and B sub-channels to be used for DAC-format output.
MS{node},MI910 (MLDT Feedback Select)
For the channel associated with this node to be used for MLDT feedback, MI910 must be set to 12. In
this mode, the pulse timer is cleared on the output pulse, and latched on the echo pulse, counting in
between at 117.96 MHz.
Station Conversion Table Processing I-Variables
The pulse timer for Servo IC m Channel n holds a number proportional to the time and therefore the
position. This must be processed in the conversion table before it can be used by the servo loop. It is best
to use the filtered parallel data conversion, a 3-line entry in the table (three consecutive MI-variables).
The MI-variables for the conversion table start at MI120.
Line 1 (Method and Address)
This 24-bit value (6 hex digits) should begin with a 3 (filtered parallel data) followed by the address of
the timer register. The possible values for this line are shown in the following table:
Encoder Conversion Table Parallel Filtered Data Format First Line for Acc-24E2A Boards
Acc-24 #
Channel 1
Channel 2
Channel 3
Channel 4
1
$30C040
$30C048
$30C050
$30C058
2
$30C060
$30C068
$30C070
$30C078
Line 2 (Bits Used Mask)
This 24-bit value should be set to $07FFFF to specify the use of the low 19 bits of the 24-bit source word.
Line 3 (Max Change)
This 24-bit value should be set to a value slightly greater than the maximum true velocity ever expected,
expressed in timer LSBs per servo cycle. With a typical MLDT, the 117.96 MHz timer LSB represents
0.024 mm (0.00094 inches); the default servo cycle is 0.442 msec.
The result of this conversion is in the X-register of the third line. Any functions using this value should
address this register. For example, if this were the first entry in the table, which starts at $000010, the
result would be in X:$0012.
Station Motor Node I-Variables
MS{anynode}, MI10x (xth Motor Node Position Loop Feedback Address)
To use the result of the conversion table for position-loop feedback for the xth motor node, MI10x should
contain the address of the result register in the conversion table - $0012 in the above example.
MS{anynode}, MI11x (xth Motor Node Absolute Position Address)
To use the MLDT for absolute power-on position for the xth motor node, set MI11x to $18xxxx (up to 24
bits of parallel Y-data) from Station address xxxx, where xxxx is the address of the timer register.
MS{anynode},MI11x xth Motor Node Absolute Position
Acc-24 #
Channel 1
Channel 2
Channel 3
Channel 4
1
$30C042
$30C04A
$30C052
$30C05A
2
$30C062
$30C06A
$30C072
$30C07A
