As part of the investigation of the problems with FAPOL in last semester a serious problem has been found with FAPOL in that it unpredictably stops working. The cause of this seems to be related to two things; the safety interlock in FASU between the FAPOL carriage mechanism and the calibration mirror and poor grounding design of the actual motor drive cards. The consequence of both of these is that the motor 18V causes drops on the digital 5V line resulting in a reset of the drive card micro-controller.
A modified code for the FAPOL drive board has been provided by CUO that should detect any loss of position of the FAPOL analysis plate.