The global event system Page: 3 of 15
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As an observation, it is not advisable to alter the R1SP or R2SP fields. You may, but then
all related egevent records must be processed again in order to recalculate their desired
position values. The MOD1 and MOD2 fields can also cause some nasty side effects if
they are altered between any two non-off modes. In general, the operating mode should be
set to off and then to some other mode if it is desired to switch between two modes.
2.2 EGEVENT Records
The EGEVENT record is used in conjunction with an EG record in order to specify a sin-
gle event that is to be placed into a sequence RAM. The event code and its time displace-
ment from the trigger are specified in this record.
2.2.1 Field Descriptions
OUT (Output Link) Used to specify what event generator link that this event is related
to. Only the Card number is used
ENM (Event Number) The event number that is to be placed into the sequence RAM.
RAM (Sequence RAM Specifier) Which RAM the event is to be placed into. (Ignored
when the generator is in 'Alternate' mode.)
DELY (Desired Delay) The desired time delay between the trigger that starts the RAM
sequence and when this event should be sent. This field must be expressed in the
units selected in the UNIT field described below.
ADLY (Actual Delay) This is a read-only field that is set to the actual delay value after
accounting for rounding caused by the clock resolution as well as collisions that
can occur if more than one event is placed into the same sequence RAM loca-
DPOS (Desired Position) This is a read-only field that represents desired position in the
sequence RAM that the event should be placed. It is expressed in clock ticks.
APOS (Actual Position) This is a read-only field that represents the actual position in
the sequence RAM that the event is placed. It is expressed in clock ticks.
UNIT (Delay Specifier Units) The time units used to express the delay value in the
DELY and ADLY fields.
VAL Placed into the record to make EPICS happy and is completely worthless.
2.2.2 Record Processing
It is intended that EGEVENT records be set to passive processing only. They are not
altered by the device support code in response to being processed. Their purpose is only to
specify the desired position and code of an event in a sequence RAM. The read-only fields
will be updated as necessary when ever the sequence RAM is reloaded. To startthings
going, however, they should have their 'process at init' flag set to YES.
Sequence RAMs are reloaded when ever any of the EGEVENT records related to it has its
DELY, ENM or UNIT values changed. It is not advisable to alter the UNIT field unless the
associated sequence RAM mode is set to 'Off'.
The Global Event System
March 2, 1994
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Winans, J. The global event system, report, March 2, 1994; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc672996/m1/3/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.