Software for Insertion Devices

ADC has developed software to control its state-of-the-art Apple II insertion devices. This type of ID uses a total of four servo motors to power ball screws at each end of the two main girders for gap and taper adjustment, and an additional four servo motors to power ball screws on each of four sub-girders for phase adjustment, comprising an 8-axis system. It's necessary to move the four girder motors in concert to precisely control magnetic gap and girder taper, and the phase motors must also be moved in concert to precisely control polarization of the produced photons.

Control hardware is based on the 1756-L62 PLC processor and Kinetix 6000 Motion Controller from Allen-Bradley. The software provides precise positioning of the girders and phases using Allen-Bradley 2.4kW servo motors and 0.1µm glass-scale linear encoders from TR Electronics. Error detection software monitors device parameters to maximize reliability and prevent beam-pipe damage. Velocity and position of all encoders are continuously monitored in order to detect encoder failure and prevent machine damage. A Graphical User Interface (GUI) was developed which communicates with the ID using TCP/IP.

EPICS Interface

ADC has interfaced the Schneider Modicon Premium PLC to EPCIS version 3.14.7 for a Wiggler built for the Australian Synchrotron Project. ASP provided an EPICS based driver for this PLC. ADC developed variables in an EPICS database to pass control parameters, status, and error conditions. ASP also provided a Redhat Linux development environment which ADC used to compile the database. An EPICS command line was used to send and receive data from the PLC using TCPIP Ethernet communications link on a Dell Laptop. This communication method was quite effective. Variables were addressed on both ends. Real, Integer, and Bit data types were passed.

ADC developed a GUI using the Schneider Modicon graphics package in the Unity Pro L development package. This provided a simple and easy way to debug and control the Wiggler for shimming and acceptance as well as verification of the EPICS interface. In addition to all motion control code, ADC also provided the PLC software to manage the correction coil update based on 20 element arrays (each) for gap, and 4 correction coils. This software interpolated the correction coil data based on gap and updated all 4 correction coils in less than 5 ms by executing in a Fast Task. The final GUI is presented below.