Meeting FESA Class Development

Date: 09-Nov-2012

Participants: L. Hechler, G. Jansa, S. Juelicher, S. Matthies, A. Reiter, A. Schwinn, U. Krause

Basis for Property description is the document 'Motion Control Software, System Design', Revision 0.2, presented by Cosylab.

Topics:

• Some base aspects are pointed out again (no objection was raised):
  • FESA classes will handle single motors and motor pairs (slits). The motors of a motor pair will be additionally represented as single motors. Data (especially setting data) will be kept consistent between the participating motors: When a slit is moved, the setting values of the singel motors are adapted and vice versa.
  • Access from the existing GSI control system will be provided, using the FESA/GSI gateway.
    It is assumed that providing the properties for the existing GSI control system can by handled completely by this Gateway, such that FESA classes don't need to consider the access from the existing GSI control system. No special FESA properties to reflect the access from the existing GSI contro system have to be implemented.
  • Synchronous movement of more than two motors will not be supported. Motor driver will only support single motors or pairs of motors. With great conffident it is assumed that apertures (four motors) always can be handled as a pair of two slits (one slit per plane). No strict synchronization between the movement of the slits will be needed (however, when movement of the both slits ist started, all four motors can move simultanously - but not strictly synchronized).
• The stands property 'Reset' is missing. It shall be contained for compatibility: All devices shall have the same set of standard properties, even when they do nothing.
• Properties 'Init' and 'Reset' are similar. Both should do some clear-up, where actions in 'Reset' must not be harder than actions in 'Init'. For stepper motors 'Init' and 'Reset' probably will do the same.
• Both properties, 'Reset' and 'Init', must not move the motors. Motors must be left at their momentary position.
• Property 'Power' shall return an error when data to switch off power is send (stepper motors don't provide remote power off). When read, 'PowerOn' shall be delivered.
• In the above mentioned document from Cosylab the description of the properties contain columns labeled 'Field name' / 'Field type'. Ment are the elements in the property-data, which in FESA terminology are called 'Value Items'.
• Property 'Status':
  • Shall also contain the 'motorStatus' value item of the property 'Acquisition'. 'Status' and 'Acquisition' both shall contain this motor status.
  • The detailed status field 'configuration changed' shall be removed.
  • When the hardware middle switch is activated, the inner limit switch will be set too (M-box fpga will set inner limit when middle switch will be active to prevent motor to move towards inner limit). After the meeting, strong opinion was to implement same functionality (set inner limit too) when middle switch has to be emulated by softwae.
  • Also for single motors a bit for 'middle switch reached' shall be included. This bit will indicate that the motor cannot be moved any further, even if the inner end switch is not yet reached.
• Property 'Version' shall contain version strings of all elements which provide version information, like FESA class version, driver version, firmware version.
• Properties to stop motor movement shall have the same name for single motors and slits.
• Setting properties to move the motors shall always initiate motor movement, even if the new position is the same as the position in the command before. Since it may happen that motor is not at position of set value (moved in local operation, fluctuations in position reference voltage), correction by sending actual position must not be prohibited
• Data in FESA properties shall be in base units only (m, s, kg). These will be converted to human friendly units in the applications. Configuration data (set by the local configuration program) should be in human friendly units (like mm, µs).
• Using FESA inheritance will not to be needed. For single motors inheritance was proposed, but implementation without inheritance will be fully sufficient.
• A first running version is planned forr end of November.
• It was mentioned that there will be major change in the FESA framework at the end of the year, which will require modifications in FESA classes which are developed with the momentary version.

Udo Krause, 9. Nov. 2012