The select record computes a value based on input obtained from up to 12 locations.
The selection algorithm can be one of the following: Specified,
High Signal,
Low Signal,
Median Signal.
Each input can be a constant,
a database link,
or a channel access link.
The record-specific fields are described below, grouped by functionality.
The select record has the standard fields for specifying under what circumstances the record will be processed. These fields are listed in Scan Fields.
The INPA-L links determine where the selection record retrieves the values from which it is to select or compute its final value. The INPA-L links are input links configured by the user to be either constants, channel access links, or database links. If channel access or database links, a value is retrieved for each link and placed in the corresponding value field, A-L. If any input link is a constant, the value field for that link will be initialized with the constant value given to it and can be modified via dbPuts.
Any links not defined are ignored by the selection record and its algorithm. An undefined link is any constant link whose value is 0. At initialization time, the corresponding value links for such fields are set to NaN, which means MISSING. The value field of an undefined link can be changed at run-time from NaN to another value in order to define the link and its field. Note that all undefined links must be recognized as such if the selection algorithm is to work as expected.
Field Summary Type DCT Default Read Write CA PP INPA Input A INLINK Yes Yes Yes No INPB Input B INLINK Yes Yes Yes No INPC Input C INLINK Yes Yes Yes No INPD Input D INLINK Yes Yes Yes No INPE Input E INLINK Yes Yes Yes No INPF Input F INLINK Yes Yes Yes No INPG Input G INLINK Yes Yes Yes No INPH Input H INLINK Yes Yes Yes No INPI Input I INLINK Yes Yes Yes No INPJ Input J INLINK Yes Yes Yes No INPK Input K INLINK Yes Yes Yes No INPL Input L INLINK Yes Yes Yes No A Value of Input A DOUBLE No Yes Yes Yes B Value of Input B DOUBLE No Yes Yes Yes C Value of Input C DOUBLE No Yes Yes Yes D Value of Input D DOUBLE No Yes Yes Yes E Value of Input E DOUBLE No Yes Yes Yes F Value of Input F DOUBLE No Yes Yes Yes G Value of Input G DOUBLE No Yes Yes Yes H Value of Input H DOUBLE No Yes Yes Yes I Value of Input I DOUBLE No Yes Yes Yes J Value of Input J DOUBLE No Yes Yes Yes K Value of Input K DOUBLE No Yes Yes Yes L Value of Input L DOUBLE No Yes Yes Yes
The selection algorithm is determined by three fields configurable by the user: the select mechanism (SELM) field, the select number (SELN) field, and the index value location (NVL) field.
The SELM field has four choices, i.e., four algorithms as follows:
Index Identifier Choice String 0 selSELM_Specified Specified 1 selSELM_High_Signal High Signal 2 selSELM_Low_Signal Low Signal 3 selSELM_Median_Signal Median Signal
The selection record's VAL field is determined differently for each algorithm.
For Specified,
the VAL field is set equal to the value field (A,
B,
C,
D,
E,
F,
G,
H,
I,
J,
K,
or L) specified by the SELN field.
The SELN field contains a number from 0-11 which corresponds to the value field to be used (0 means use A; 1 means use B,
etc.).
How the NVL field is configured determines,
in turn,
SELN's value.
NVL is an input link from which a value for SELN can be retrieved,
Like most other input links NVL can be a constant,
or a channel access or database link.
If NVL is a link,
SELN is retrieved from the location in NVL.
If a constant,
SELN is initialized to the value given to the constant and can be changed via dbPuts.
The High Signal,
Low Signal,
and Median Signal algorithms do not use SELN or NVL.
If High Signal is chosen,
VAL is set equal to the highest value out of all the defined value fields (A-L).
If Low Signal is chosen,
VAL is set equal to lowest value of all the defined fields (A-L).
And if Median Signal is chosen,
VAL is set equal to the median value of the defined value fields (A-L).
(Note that these algorithms select from the value fields; they do not select from the value field index.
For instance,
Low Signal will not select the A field's value unless the value itself is the lowest of all the defined values.)
Field Summary Type DCT Default Read Write CA PP SELM Select Mechanism MENU (selSELM) Yes Yes Yes No SELN Index value USHORT No Yes Yes No NVL Index Value Location INLINK Yes Yes Yes No
These parameters are used to present meaningful data to the operator. They display the value and other parameters of the select record either textually or graphically.
EGU is a string of up to 16 characters describing the units that the selection record manipulates.
It is retrieved by the get_units record support routine.
The HOPR and LOPR fields set the upper and lower display limits for the VAL,
HIHI,
HIGH,
LOW,
and LOLO fields.
Both the get_graphic_double and get_control_double record support routines retrieve these fields.
The PREC field determines the floating point precision with which to display VAL.
It is used whenever the get_precision record support routine is called.
See Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.
Field Summary Type DCT Default Read Write CA PP EGU Engineering Units STRING [16] Yes Yes Yes No HOPR High Operating Rng DOUBLE Yes Yes Yes No LOPR Low Operating Range DOUBLE Yes Yes Yes No PREC Display Precision SHORT Yes Yes Yes No NAME Record Name STRING [61] No Yes No No DESC Descriptor STRING [41] Yes Yes Yes No
The possible alarm conditions for select records are the SCAN, READ, and limit alarms. The SCAN and READ alarms are called by the record or device support routines. The limit alarms are configured by the user in the HIHI, LOLO, HIGH, and LOW fields using numerical values. They specify conditions for the VAL field. For each of these fields, there is a corresponding severity field which can be either NO_ALARM, MINOR, or MAJOR. Alarm Fields lists the fields related to alarms that are common to all record types.
Field Summary Type DCT Default Read Write CA PP HIHI Hihi Alarm Limit DOUBLE Yes Yes Yes Yes HIGH High Alarm Limit DOUBLE Yes Yes Yes Yes LOW Low Alarm Limit DOUBLE Yes Yes Yes Yes LOLO Lolo Alarm Limit DOUBLE Yes Yes Yes Yes HHSV Hihi Severity MENU (menuAlarmSevr) Yes Yes Yes Yes HSV High Severity MENU (menuAlarmSevr) Yes Yes Yes Yes LSV Low Severity MENU (menuAlarmSevr) Yes Yes Yes Yes LLSV Lolo Severity MENU (menuAlarmSevr) Yes Yes Yes Yes HYST Alarm Deadband DOUBLE Yes Yes Yes No
These fields are configurable by the user. They are used as deadbands for the archiver and monitor calls for the VAL field. Unless, VAL changes by more than the value specified by each, then the respective monitors will not be called. If these fields have a value of zero, everytime the VAL changes, monitors are triggered; if they have a value of -1, everytime the record is processed, monitors are triggered.
Field Summary Type DCT Default Read Write CA PP ADEL Archive Deadband DOUBLE Yes Yes Yes No MDEL Monitor Deadband DOUBLE Yes Yes Yes No
These parameters are used by the run-time code for processing the selection record. They are not configurable prior to run-time, nor are they modifiable at run-time. They represent the current state of the record. The record support routines use some of them for more efficient processing.
The VAL field is the result of the selection record's processing. It can be accessed in the normal way by another record or through database access, but is not modifiable except by the record itself. The LALM, ALST, and the MLST are used to implement the HYST, ADEL, and MDEL hysteresis factors for the alarms, archiver, and monitors, respectively.
The LA-LL fields are used to implement the monitors for each of the value fields, A-L. They represent previous input values. For example, unless LA is not equal to A, no monitor is invoked for A.
Field Summary Type DCT Default Read Write CA PP VAL Result DOUBLE Yes Yes No No LALM Last Value Alarmed DOUBLE No Yes No No ALST Last Value Archived DOUBLE No Yes No No MLST Last Val Monitored DOUBLE No Yes No No LA Prev Value of A DOUBLE No Yes No No LB Prev Value of B DOUBLE No Yes No No LC Prev Value of C DOUBLE No Yes No No LD Prev Value of D DOUBLE No Yes No No LE Prev Value of E DOUBLE No Yes No No LF Prev Value of F DOUBLE No Yes No No LG Prev Value of G DOUBLE No Yes No No LH Prev Value of H DOUBLE No Yes No No LI Prev Value of I DOUBLE No Yes No No LJ Prev Value of J DOUBLE No Yes No No LK Prev Value of K DOUBLE No Yes No No LL Prev Value of L DOUBLE No Yes No No
long (*init_record)(struct dbCommon *precord, int pass)
IF NVL is a constant, SELN is set to its value. If NVL is a PV_LINK a channel access link is created.
For each constant input link, the corresponding value field is initialized with the constant value (or NaN if the constant has the value 0).
For each input link that is of type PV_LINK, a database or channel access link is created.
long (*process)(struct dbCommon *precord)
See "Record Processing".
long (*get_units)(struct dbAddr *paddr, char *units)
Retrieves EGU.
long (*get_precision)(const struct dbAddr *paddr, long *precision)
Retrieves PREC.
long (*get_graphic_double)(struct dbAddr *paddr, struct dbr_grDouble *p)
Sets the upper display and lower display limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.
long (*get_control_double)(struct dbAddr *paddr, struct dbr_ctrlDouble *p)
Sets the upper control and the lower control limits for a field. If the field is VAL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR, else if the field has upper and lower limits defined they will be used, else the upper and lower maximum values for the field type will be used.
long (*get_alarm_double)(struct dbAddr *paddr, struct dbr_alDouble *p)
Sets the following values:
upper_alarm_limit = HIHI upper_warning_limit = HIGH lower_warning_limit = LOW lower_alarm_limit = LOLO
Routine process implements the following algorithm: