Research On Synchronous Control Technology Of SSRF Beamline Station

The synchrotron radiation experimental technology at Shanghai Synchrotron Radiation Facility(SSRF)requires real-time control and data acquisition of multiple physical parameters and multiple dimensions.The key technology lies in the fly scanning between the beamline equipments and detectors.Currently the fly scanning technology is implemented by extracting the control pulse signals from the MAXv-8000 to a scaler and calculating the counts of the pulse signal because the MAXv-8000 does not have the synchronous trigger function.This method not only makes the system more complicated,but also the control pulse signal counting does not accurately match the motor real position when the motor loses steps.Therefore,it is necessary to study a new synchronization control technology,which can realize multi-dimensional motion control and synchronous triggering function.Furtherfore,the synchronization precision is required to reach the order of microseconds.By investigating the Advanced Synchrotron Radiation Facilities in the world,the Power UMAC(Universal Motion and Automation Controller)controller of Delta Tau Data System of the United States is selected to accomplish the fly scanning between the motion control and data acquisition system.The paper has mainly completed the following work.1)Establishing the hardware system with UMAC controller as the core module,with the expansion board ACC-24E2 S to control the movement of the stepper motor.With the position capture and comparison function,when the motor moves to the pre-defined position,a hardware synchronization signal is output to trigger to acquire the photodiode data.2)The motion control system software architecture is designed,performing the hardware parameter configurations and developing the motion program with the programming language Power PMAC Script to execute the motion control and synchronization signal output.3)The data acquisition system of the galvanometer to collect photodiode readings is developed under the EPICS(Experimental Physics and Industrial System)platform,which fulfills the precise synchronization with the data acquisition system during the flying scanning of the stepper motor.The system was online tested at SSRF X-ray test beamline by measuring the rocking curve of the exit beam from the Monochromator.The results show that the error of the full-width at half maximum(FWHM)is about 0.17% by comparing the one with the step by step scanning which is popular used as the normal method.It also shows the fly scanning synchronization accuracy reaches sub-microsecond level,meeting the requirement of advanced experimental methods.