EPICS Record Reference Manual. Philip Stanley, Janet Anderson, Marty Kraimer. Wikified by Andrew Johnson. Copyright · Preface. EPICS Input Output Controller (IOC) Record Reference Manual. Janet B. Anderson and. Martin R. Kraimer. Advanced Photon Source. Issue 1: December 1. EPICS R Channel Access Reference Manual .. link -nologo /LTCG / incremental:no /opt:ref /release /version -out: acctst. obj .. by the EPICS record support (see the EPICS Application Developer Guide ).

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The calculation or “Calc” record is used to perform algebraic, relational, and logical operations on values retrieved from other records. The result of its operations can then be accessed by another record so that it can be used.

The Calc record has the standard fields for specifying under what circumstances the record will be processed. These fields are listed in Scan Fields.

In addition, Scanning Specification explains how these fields are used. The fields can be database links, channel access links, or constants.

RRM 3-14 Calculation

If they are links, they must specify another record’s field or a channel access link. If they are constants, they will be initialized with the value they are configured with and can be changed via dbPuts.

They cannot be hardware addresses. See Address Specification for information on how to specify database links. The CALC field contains the infix expression which the record routine will use when it processes the record. The resulting value is placed in the VAL field and can be accessed from there. It is this expression which is actually used to calculate VAL. The Reverse Polish expression is evaluated more epiics during run-time than recrod infix expression.

CALC can be changed at run-time, and a special record recore calls a function to convert it to Reverse Polish Notation.

The infix expressions that can be used are very similar to the C expression syntax, but with some additions and subtle differences in operator meaning and precedence. The string may contain a series of expressions separated by a semi-colon character ‘;’ any one of which may actually provide the calculation result; however all of the other expressions included must assign their result to a variable.

Elics alphabetic elements described below are case independent, so upper and lower case letters may be used and mixed in the variable and function names as desired. Spaces may be used anywhere within an expression except between the characters that make up a single expression element. The range of expressions supported reverence the calculation record are separated into literals, constants, operands, algebraic operators, trigonometric operators, relational operators, logical operators, the assignment operator, parentheses and commas, and the question mark or ‘?: The expression uses the values retrieved from the INP x links as operands, though constants can be used as operands too.


These values retrieved recodd the input links are stored in the A-L fields. The values to be used in the expression are simply referenced by the referejce letter.

RRM Calculation – EPICSWIKI

Also, the RNDM nullary function can be included as an operand in the expression in order to generate a random number between 0 and 1. Epica keyword VAL returns the current contents of the VAL field which can be written to by a CA put, so it might not be the result from last time the expression was evaluated.

The semicolon is used to separate expressions.

Although only one traditional calculation expression is allowed, multiple assignment expressions are allowed. Prior to Base 3. These parameters are used to present meaningful data to the operator. These fields are used to display VAL and the other parameters of the calculation record either textually or graphically.

The EGU field contains a string of up to 16 characters which is supplied by the user and which describes the values being operated upon. The EGU string is solely for an operator’s sake and does not have to be used. The Calculation alarm is called by the record processing routine when the CALC expression epica an invalid one, upon which an error message is generated. The following alarm refereence which are configured by the user define the limit alarms for the VAL field and the severity corresponding to those conditions.

The HYST field defines an alarm deadband for each limit. See Alarm Specification for a complete explanation of alarms and these fields. Alarm Fields lists other fields related to alarms that are common to all record types. These parameters are used to determine when to send monitors for the value fields. The monitors are sent when the value field exceeds the last monitored field by the appropriate deadband, the ADEL for archiver monitors and the MDEL field for all other types of monitors.


If these fields have a value of zero, everytime the value changes, monitors are triggered; if they have a value of -1, everytime the record is scanned, monitors are triggered. See Monitor Specification for a complete explanation of monitors. These fields are not configurable using a configuration too and none are modifiable at run-time.

They are used to process the record. The LA-LL fields are used to decide when to trigger monitors for the corresponding fields. For instance, if LA does not equal the value for A, monitors for A are triggered.

A routine postfix is called to convert the infix expression in CALC to reverse polish notation. The result is stored in RPCL.

Sets the upper display and lower display limits for a field. Sets the upper control and the lower control limits for a field.

Retrieved from ” https: This page was last edited on 22 Marchat Browse Main page Recent changes Random page Help. This page Page Discussion History. No Literals Standard double precision floating point numbers Inf: Not a Number Constants PI: Yes The keyword VAL returns wpics current contents of the VAL field which can be written to by a CA put, so it might not be the result from last time the expression was evaluated.

Absolute value unary SQR: Square root unary MIN: Minimum any number of args MAX: Log base 10 unary LOGE: Natural log unary LN: Natural log unary EXP: Right shift Assignment Operator: Nested parenthesis are supported. The comma is supported when used to separate the arguments of a binary function.

Conditional Expression The C language’s question mark operator is mmanual. No Monitor Parameters These parameters are used to determine when to send monitors for the value fields. No Run-time Parameters These fields are not configurable using a configuration too and none are modifiable at run-time. The LALM field is used to implement the hysteresis factor for the alarm limits.