Chapter 31: State

1. Introduction

The state record is a means for a state program to communicate with the operator interface. Its only function is to provide a place in the database through which the state program can inform the operator interface of its state by storing an arbitrary ASCII string in its VAL field. The state record fields fall into the following categories:

scan parameters

operator display parameters

other parameters

2. Scan Parameters

The state record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in Scan Fields, Chapter 2, 2. In addition, Scanning Specification, Chapter 1, 1, explains how these fields are used.

3. Operator Display Parameters

See Chapter 2, Fields Common to All Record Types, for more on the record name (NAME) and description (DESC) fields.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
NAME	Record Name	STRING [29]	Yes	0	Yes	No	No
DESC	Description	STRING [29]	Yes	Null	Yes	Yes	No	No

4. Alarm Parameters

The state record has the alarm parameters common to all record types. Alarm Fields, Chapter 2, 3, lists other fields related to a alarms that are common to all record types.

5. Run-time Parameters

These parameters are used by the application code to convey the state of the program to the operator interface. The VAL field holds the string retrieved from the state program. The OVAL is used to implement monitors for the VAL field. When the string in OVAL differs from the one in VAL, monitors are triggered. They represent the current state of the sequence program.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
VAL	Value Field	STRING [20]	Yes	Null	Yes	Yes	Yes	Yes
OVAL	Old Value	STRING [20]	No	Null	Yes	No

6. Record Support Routines

Two record support routines are provided:

process

process triggers monitors on VAL when it changes and scans the forward link if necessary.

get_value

get_value fills in struct valueDes so that it refers to VAL.

1. - Introduction
2. - Scan Parameters
3. - Operator Display Parameters
4. - Alarm Parameters
5. - Run-time Parameters
6. - Record Support Routines
process
get_value

EPICS Record Reference Manual - 19 MAY 1998

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