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Motion Control
The information below is currently used on LARMOR. It could easily be generalised for any instrument.
Fixed setpoints for sample changers and IN/OUT positions for beam monitors are defined in appropriately named text files held in the C:\Instrument\Settings\config\NDXLARMOR\motionSetPoints\ directory.
For example: The IN and OUT positions for Monitors 3 and 4 are defined in the following files:
c:\Instrument\Settings\config\NDXLARMOR\motionSetPoints\monitor3.txt
c:\Instrument\Settings\config\NDXLARMOR\motionSetPoints\monitor4.txt
These instructions are also present in the following file: C:\Instrument\Docs\motion_control\fixed_setpoints.txt.
From the motion control point of view the two devices are identical. Each has a motor with an IN and an OUT position, like monitors 3 and 4. Each also has a motor to control the angle. The motor moves in a straight line tangential to the axis, so the transformation is angle = tan (motor position / separation).
The conversion is performed using a soft motor, as documented in the motor record. Note that soft motors require devSoftMotor.dbd and softMotor.dll to be included.
The setpoint lookup files for these devices define positions for both motors.
The two-tier sample changer contains four slots, each of which holds a rack. Several different types of rack are available. The positions of the slots and the layouts of the different types of rack are defined in rack_definitions.xml. It is unlikely these will need to change often.
The current state of the sample changer, i.e. which rack type is loaded into each slot and the offsets of the racks compared to their nominal positions, isstored in samplechanger.xml.
Putting to the PV SAMPCHNG:RECALC will cause these files to be read and a new sample position lookup file to be generated and loaded. This can be done by pressing recalculate in the Sample Changer OPI.
Please see the following page for guidance: Limits
Please see the following page for guidance: Home