The previous value of VDES is subtracted from the new value of VDES and the difference used to calculate the needed number of steps to move the device. No attempt is made to wait for the device to actually complete the motion and no check is performed. The reset function is used to initialize devices after a crate is powered on. For stepping motors it must write SPED, the speed and acceleration time, to the controller if speed is programmable. In addition, the appropriate SAM's are reset to IEEE mode as for magnets, and all previously trimmed devices are re-trimmed.
Necessary revisions are minor.
Only minor revisions are required to handle the alternate secondary names. The magnet checkout knob routine when used for stepping motors reads the two SAM channels assigned to the STEP and uses the DVA or DVAC polynomial to calculate the current 'absolute' DAC setting. This is used as the starting point for the knob. Knob turns are treated as increments and written directly to the STEP's DAC register. The display is an expansion of the normal magnet checkout display and includes the DAC increment, equivalent 'absolute' DAC setting, status register, both SAM channels and ripple measured on each, calculated cursor position and status.