Control systems of neutron instruments are responsible for the movement of a variety of mechanical axes. In the TANGO based control systems developed by Forschungszentrum Jülich for neutron instruments, Siemens S7-300 PLCs with single axis stepper motor controllers from Siemens or Phytron have been used for this purpose in the past. Synchronous coordinated movement of several axes has been implemented with dedicated 4-axes NC modules (FM357) for the S7-300. In future, the recent S7-1500 PLC family shall be used for motion tasks. With the S7-1500, stepper motor control is possible with low-cost fast digital outputs, so called PTOs (pulse trade outputs). The integrated motion functions of the S7-1500 directly support synchronous movement. The function block interface defined by PLCopen serves as a homogeneous programming interface which is independent of a specific motion controller. For the single crystal diffractometer HEiDi at the research reactor FRM-II a replacement for a S7-300 with FM357 has been implemented based on a S7-1500 PLCs and a PTO module
