Advanced Photon Source

An Office of Science National User Facility

APS Beamline Steering PV Information

APS Beamlines can issue steering request via EPICS PVs (PDF icon SlideShow). There is an MEDM screen available.

Beamline Optimization PV

IDxx:SteeringGoodness  - Optimization feedback value.Must be at a maximum when the beam position is best
- Used only at ID beamlines for sector steering optimizations (xx = two digit sector number)

Steering Display and Variables

BLSteering.adl - Should be located on all DSERVs at
      sNNdserv:/APSshare/adlsys/sr/id/BLSteering.adl
Substitutions are:
  • BL = ID or BM
  • S = 2-digit sector number for sector steering (i.e. 01)
    • 2-digit sector number plus us or ds for canted steering (i.e. 12us or 12ds)
  • SEC = Single digit sector number for SR BPM V and H angle PVs

Steering PV's

Below variables:
BL = ID or BM
xx = 2-digit sector number (i.e. 01)
yy = us or ds (Only used for canted beamlines)
BLxxyy:BLSaveSteerReq - Reserved for possible future use
BLxxyy:EnableSteering - Is steering enabled/allowed (binary value)
0 - Steering Enabled
1 - Steering Disabled
 
BLxxyy:MaxXpLimit - User settable maximum allowed steering limit in X-plane
BLxxyy:MinXpLimit - User settable minimum allowed steering limit in X-plane
BLxxyy:MaxYpLimit - User settable maximum allowed steering limit in Y-plane
BLxxyy:MinYpLimit - User settable minimum allowed steering limit in Y-plane
 
BLxxyy:BLSteeringXp - User input how much steering in X-plane
Must be non-zero and within above min and max X-plane limits
BLxxyy:BLSteeringYp - User input how much steering in Y-plane
Must be non-zero and within above min and max Y-plane limits
 
BLxxyy:RequestSteering - Button for requesting steering (toggle to 1 then to zero)
 
BLxxyy:XpRunAccum - Total amount of steering for current run period in X-plane (not user resettable)
BLxxyy:YpRunAccum - Total amount of steering for current run period in Y-plane (not user resettable)
 
BLxxyy:XpAccumulator - Total amount of steering requested for all requests in X-plane since the last time it was reset 
BLxxyy:YpAccumulator - Total amount of steering requested for all requests in Y-plane since the last time it was reset 
BLxxyy:TotalSteerRst - Reset button for actual accumulators (toggle to 1 then to zero)
 
BLxxyy:XpActualAccum - Total amount of steering actually done for all requests in X-plane since the last time it was reset
BLxxyy:YpActualAccum - Total amount of steering actually done for all requests in Y-plane since the last time it was reset
BLxxyy:BLTotalSteerRst - Reset button for request accumulators (toggle to 1 then to zero)
 
 
BLxxyy:BLSteeringReqTS - Time stamp for steering request (string)
BLxxyy:BLSteeringFinTS - Time stamp for steering completed (string)
BLxxyy:SteerCheck - Not user writable, processed when IDxx:RequestSteering button is pressed
Check if requested steering amount + total run accumulation will be user settable limits
String messages appear in IDxx:BLSteeringErrMsg PV
0 - Everything is OK, clears IDxx:BLSteeringErrMsg PV
1 - "Max Steering Exceeded"
2 - "Min Steering Exceeded"
 
BLxxyy:CheckSteerVals - Checks to see if IDxx:SteerCheck is zero and that steering has been requested and that steering amount requested is non-zero
If all checks are ok then sends steering request to the server in MCR
 
BLxxyy:SteeringCount - How many times steering has been requested (this run?)
BLxxyy:SteeringEnable - Steering enabled when 0, disabled when 1 (not user writable)
Enables/disables record processing in EPICS database
 
BLxxyy:BLSteeringMsg - General steering messages appear here (Variable undefined string messages)
BLxxyy:BLSteeringErrMsg - Error messages appear here (Variable undefined string messages)
BLxxyy:BLSteerStatus - Predefined steering messages (other messages may be defined later)
STATE  0: No Steering Requested - User has not requested steering, usually after IOC reboot only
STATE  1: Steering Requested - User requested steering (transient)
STATE  2: Steering In Progress - Server has gotten steering request
STATE  3: Steering Complete - Server has completed steering
STATE  4: Other steering - Other beamline steering in progress
STATE  5: System Unavail - MCR has disabled automatic steering due to other issues
 
BLxxyy:OrbitCorrConfigX - Information about orbit correction configuration
BLxxyy:OrbitCorrConfigY - Information about orbit correction configuration
BLxxyy:XrayBpmsInUseX - Tells if X-Ray BPMs are in use for X-plane orbit control; values are Enabled or Disabled
BLxxyy:XrayBpmsInUseY - Tells if X-Ray BPMs are in use for Y-plane orbit control; values are Enabled or Disabled
 

Steering Access Security

The access security mode for beamline steering PVs (ID and BM) is based on the sectors insertion device access security mode.

To gain write access to the PVs the insertion device(s) must be in User Access mode. If there are 2 IDs then both must be in User Access mode.