Energy macros and notes (updated November 1999)

The standard Spec energy macros assign the monochromator motor positions directly to control the energy. Although some sites use these macros along with the Epics monochromator control, CMC has decided to avoid the potential for Spec and Epics to disagree about the motor positions for a given energy.

Instead, an "energy" pseudomotor record has been built in epics, made to look like a stepper motor to Spec. This "motor" is called kmono and takes the energy in keV as the argument. The necessary revisions to the standard energy macros have been put into the file energyCMC.mac.

Another important installation note: to make the energy macros consistent with SRI-CAT Kohzu macros, we changed the Spec mnemonics for the following two motors:

  1. 9ida:m12 -- mon_y (was koh1y)
  2. 9ida:m14 -- mon_z (was koh2z)
This keeps us from having to redefine the _assign_mono macro.

The file SPECD/site.mac, which Spec runs automatically on startup, also contains monochromator initialization commands.

The energy macros, including the setE command, were all tested in November 1999 and we found no problems. I'd recommend that users avoid doing ordinary motor scans (ascan, lup, etc) of the pseudomotor kmono. Spec will not know that LAMBDA is changing unless the energy macros are used instead: getE, moveE, setE, Escan.

EXAFS users should be aware that Escan is the basic energy scan defined in Spec. There are also macros called setreg and doreg in the standard distribution (see region.mac). These allow the user to modify a basic scan by interactively defining any number of regions, each with their own endpoints, intervals, and count time, then run the set of (separate) scans. Here is a text example. A number of EXAFS beamlines use Spec; fancier macros are rumored to exist at CHESS and the ESRF.