Aperture Field Diaphragm

• Control of the Aperture Field Diaphragm.
  The device is controlled by the STRAP LCU Control Software.



• The control is deployed on the Sensor LCU.

Hardware Interface:

The hardware interfaces are described in [AD 08].

Software Interface:

The control of the device is based on the VLT Motor Control Software (MCM), see [RD 09].

Item	From	To	Command/Action	Parameter		Unit	Note
				Command	Reply
SET APERTURE FIELD DIAMETER:
1	ATCS	STRAP	Send command SETAFD	diameter		arcsec	1
AUTOMATIC APERTURE FIELD DIAMETER SETTING:
2	ATCS	STRAP	Send command AUTOAFD	sky background		ph/s	2

Note 1: The AFD device is not yet integrated within the STRAP Control Software running on the LCU. The STRAP Control Software is responsible of this function. As of Release 1, STRAP does not support automatic aperture diaphragm setting.
For maintenance/tests purposes, the ATCS should also be able to control the diaphragm.

Note 2: This command, planned for a future Release, needs the sky background value for automatically setting the diaphragm diameter. This value might be obtained from a TCCD exposure before starting field stabilization.

Last modified: Thu Nov 18 09:11:11 MET 1999