Calculation Record (calc)

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 then be used.

Parameter Fields

The record-specific fields are described below, grouped by functionality.

Scan Parameters

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

Read Parameters

The read parameters for the Calc record consist of 12 input links INPA, INPB, ... INPL. The fields can be database links, channel access links, or constants. 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.

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

Field	Summary	Type	DCT	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

Expression

At the core of the Calc record lies the CALC and RPCL fields. The CALC field contains the infix expresion 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. The CALC expression is actually converted to opcode and stored as Reverse Polish Notation in the RPCL field. It is this expression which is actually used to calculate VAL. The Reverse Polish expression is evaluated more efficiently during run-time than an infix expression. CALC can be changed at run-time, and a special record routine 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. All 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 characters that make up a single expression element.

The range of expressions supported by 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 '?:' operator.

Field Summary Type DCT Default Read Write CA PP

CALC Calculation STRING [80] Yes Yes Yes Yes

RPCL Reverse Polish Calc NOACCESS No No No No

Field	Summary	Type	DCT	Default	Read	Write	CA PP
CALC	Calculation	STRING [80]	Yes		Yes	Yes	Yes
RPCL	Reverse Polish Calc	NOACCESS	No		No	No	No

Literals

Standard double precision floating point numbers
Inf: Infinity
Nan: Not a Number

Constants

PI: returns the mathematical constant π
D2R: evaluates to π/180 which, when used as a multiplier, converts an angle from degrees to radians
R2D: evaluates to 180/π which as a multiplier converts an angle from radians to degrees

Operands

The expression uses the values retrieved from the INPx links as operands, though constants can be used as operands too. These values retrieved from the input links are stored in the A-L fields. The values to be used in the expression are simply referenced by the field letter. For instance, the value obtained from INPA link is stored in the field A, and the value obtained from INPB is stored in field B. The field names can be included in the expression which will operate on their respective values, as in A+B. 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.

Field Summary Type DCT Default Read Write CA PP

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

Field	Summary	Type	DCT	Read	Write	CA PP
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 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 the last time the expression was evaluated).

Algebraic Operators

ABS: Absolute value (unary)
SQR: Square root (unary)
MIN: Minimum (any number of args)
MAX: Maximum (any number of args)
FINITE: returns non-zero if none of the arguments are NaN or Inf (any number of args)
ISNAN: returns non-zero if any of the arguments is NaN or Inf (any number of args)
CEIL: Ceiling (unary)
FLOOR: Floor (unary)
LOG: Log base 10 (unary)
LOGE: Natural log (unary)
LN: Natural log (unary)
EXP: Exponential function (unary)
^ : Exponential (binary)
** : Exponential (binary)
+ : Addition (binary)
- : Subtraction (binary)
* : Multiplication (binary)
/ : Division (binary)
% : Modulo (binary)
NOT: Negate (unary)

Trigonometric Operators

SIN: Sine
SINH: Hyperbolic sine
ASIN: Arc sine
COS: Cosine
COSH: Hyperbolic cosine
ACOS: Arc cosine
TAN: Tangent
TANH: Hyperbolic tangent
ATAN: Arc tangent

Relational Operators

>= : Greater than or equal to
> : Greater than
<= : Less than or equal to
< : Less than
# : Not equal to
= : Equal to

Logical Operators

&& : And
|| : Or
! : Not

Bitwise Operators

| : Bitwise Or
& : Bitwise And
OR : Bitwise Or
AND : Bitwise And
XOR : Bitwise Exclusive Or
~ : One's Complement
<< : Arithmetic Left Shift
>> : Arithmetic Right Shift
>>> : Logical Right Shift

Assignment Operator

:= : assigns a value (right hand side) to a variable (i.e. field)

Parantheses, Comma, and Semicolon

The open and close parentheses are supported. Nested parentheses are supported.

The comma is supported when used to separate the arguments of a binary function.

The semicolon is used to separate expressions. Although only one traditional calculation expression is allowed, multiple assignment expressions are allowed.

Conditional Expression

The C language's question mark operator is supported. The format is: condition ? True result : False result

Expression Examples

Algebraic

A + B + 10

Result is A + B + 10

Relational

(A + B) < (C + D)

Result is 1 if (A + B) < (C + D)
Result is 0 if (A + B) >= (C + D)

Question Mark

(A + B) < (C + D) ? E : F + L + 10

Result is E if (A + B) < (C + D)
Result is F + L + 10 if (A + B) >= (C + D)

Prior to Base 3.14.9 it was legal to omit the : and the second (else) part of the conditional, like this:

(A + B)<(C + D) ? E

Result is E if (A + B)<(C + D)
Result is unchanged if (A + B)>=(C + D): From 3.14.9 onwards, this expresion must be written as (A + B) < (C + D) ? E : VAL

Logical

A & B

Causes the following to occur:
- Convert A to integer
- Convert B to integer
- Bitwise And A and B
- Convert result to floating point

Assignment

sin(a); a:=a+D2R

Causes the Calc record to output the successive values of a sine curve in 1 degree intervals.

Operator Display Parameters

These parameters are used to present meaningful data to the operator. These fields are used to display VAL and 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 string is retrieved whenever the routine get_units is called. The EGU string is solely for an operator's sake and does not have to be used.

The HOPR and LOPR fields only refer to the limits of the VAL, HIHI, HIGH, LOW and LOLO fields. PREC controls the precision of the VAL field.

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

PREC Display Precision SHORT Yes Yes Yes No

HOPR High Operating Rng DOUBLE Yes Yes Yes No

LOPR Low Operating Range DOUBLE Yes Yes Yes No

NAME Record Name STRING [61] No Yes No No

DESC Descriptor STRING [41] Yes Yes Yes No

Field	Summary	Type	DCT	Read	Write	CA PP
EGU	Engineering Units	STRING [16]	Yes	Yes	Yes	No
PREC	Display Precision	SHORT	Yes	Yes	Yes	No
HOPR	High Operating Rng	DOUBLE	Yes	Yes	Yes	No
LOPR	Low Operating Range	DOUBLE	Yes	Yes	Yes	No
NAME	Record Name	STRING [61]	No	Yes	No	No
DESC	Descriptor	STRING [41]	Yes	Yes	Yes	No

Alarm Parameters

The possible alarm conditions for the Calc record are the SCAN, READ, Calculation, and limit alarms. The SCAN and READ alarms are called by the record support routines. The Calculation alarm is called by the record processing routine when the CALC expression is an invalid one, upon which an error message is generated.

The following alarm parameters 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 of these fields. Alarm Fields lists other 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

Field	Summary	Type	DCT	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

Monitor Parameters

These paramaeters are used to determine when to send monitors for the value fields. These 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.

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

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

Run-time Parameters

These fields are not configurable using a configuration tool and none are modifiable at run-time. They are used to process the record.

The LALM field is used to implement the hysteresis factor for the alarm limits.

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 A, monitors for A are triggered. The MLST and ALST fields are used in the same manner for the VAL field.

Field Summary Type DCT Default Read Write CA PP

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

Field	Summary	Type	DCT	Read	Write	CA PP
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

Record Support

Record Support Routines

`init_record`

For each constant input link, the corresponding value field is initialized with the constant value if the input link is CONSTANT or a channel access link is created if the input link is a PV_LINK.

A routine postfix is called to convert the infix expression in CALC to Reverse Polish Notation. The result is stored in RPCL.

`process`

See next section.

`special`

This is called if CALC is changed. special calls postfix.

`get_units`

Retrieves EGU.

`get_precision`

Retrieves PREC.

`get_graphic_double`

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 will be used.

`get_control_double`

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.

`get_alarm_double`

Sets the following values:

upper_alarm_limit = HIHI

upper_warning_limit = HIGH

lower_warning_limit = LOW

lower_alarm_limit = LOLO

Record Processing

Routine process implements the following algorithm:

1. Fetch all arguments.
2. Call routine calcPerform, which calculates VAL from the postfix version of the expression given in CALC. If calcPerform returns success UDF is set to FALSE.
3. Check alarms. This routine checks to see if the new VAL causes the alarm status and severity to change. If so, NSEV, NSTA, and LALM are set. It also honors the alarm hysteresis factor (HYST). Thus the value must change by at least HYST before the alarm status and severity changes.
4. Check to see if monitors should be invoked.

Alarm monitors are invoked if the alarm status or severity has changed.
Archive and values change monitors are invoked if ADEL and MDEL conditions are met.
Monitors for A-L are checked whenever other monitors are invoked.
NSEV and NSTA are reset to 0.

5. Scan forward link if necessary, set PACT FALSE, and return.