4.10 Computer Control of GEM Choppers

The GEM choppers are described in section 2.3

Manual control of the choppers is described in section 3.4

Here are camac commands, for use on the GEM VMS computer, to control the disc choppers:

Do not attempt to do computer control of frequency (C_SPD6) or to stop (C_STOP6) or start (C_START6) the choppers – this is not currently available.

The chopper delays may be set by these commands …

CSET C_PHS6 19302

CSET C_PHS9 19493

The current values can be read by…

CSH C_PHS6/ENQ

  Note that this returns the actual value (not the requested value).

 In the future frequency will be set by…

  CSET C_SPD6

  And stopping and starting will be done by…

  CSET C_STOP6 0

  CSET C_START6 0

  where 0 is a dummy value (i.e. you must put something here, but it doesn’t matter what you put).

Last updated on 25 Feb 2003 by Alex Hannon (a.c.hannon@rl.ac.uk)