Ndrive HP Options
Ndrive HP 10/20/30 User’s Manual
4-20 www.aerotech.com
Example
:
It is desired to generate a pulse output every 1,000 encoder counts in -DUALPSO or
-TRIPLEPSO mode. The individual axis speeds approach 20 MHz. during the
motion and therefore exceed the 5 MHz. -DUALPSO or -TRIPLEPSO tracking
limitation. The PSOTRACK <axis> SCALE 4 4 command must be used and the
PSODISTANCE values reduced by a factor of 4 as follows…
PSODISTANCE X FIXED 250 STEPS ; distance specified with ¼
; actual resolution
B)
In order to run the servo loop at full encoder resolution and data rates above 20 MHz.,
Ndrive software versions 2.02 and above contain the CfgFbkEncMxhQuadDiv axis
parameter which acts as an MXH output divider. This parameter allows you to specify a
lower resolution for the MXH quadrature output signal only (used by -DUALPSO or -
TRIPLEPSO options on other drives). The effective resolution is the full resolution, as
derived using CfgFbkEncMultFactorMXH axis parameter, divided by the
CfgFbkEncMxhQuadDiv axis parameter.
The servo loop always runs at the full resolution as
determined by the CfgFbkEncMultFactorMXH axis
parameter. The CfgFbkEncMxhQuadDiv axis parameter
does not affect servo loop resolution.
Example
:
An application uses a 4um linear encoder with an MXH option on an Ndrive. It is
desired to move the motor at a maximum speed of 200mm/second and track using
the -DUALPSO or -TRIPLEPSO option.
CfgFbkEncMultFactorMXH = 500 ; value for 2nm servo loop
; resolution
Encoder resolution = 250 lines /mm * 500 * 4 = 500,000 counts / mm (2nm)
Encoder data rate at 200mm/sec = 500,000 * 200 = 100Mhz
This exceeds the -DUALPSO or -TRIPLEPSO maximum encoder tracking rate of 5
MHz. and must be reduced by 100/5 = 20. Set the CfgFbkEncMxhQuadDiv axis
parameter to 20 to achieve this. The user must now program the PSODISTANCE
command in units of 40nm instead of 2 nm.
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