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Data access

Current values
Historical data
ESL RPC procedure call
Limitations
Description of columns containing status information

Current values


Basic current values are sorted out by a value type into the following five tables.

1. AnalogPoints - real values and relative time values.

COLUMN NAME VALUE TYPE SIZE
NAME CHAR 64
DESCRIPT CHAR 50
VALUE DOUBLE  8
STATUS INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

2. IntegerPoints - integer values.

COLUMN NAME VALUE TYPE SIZE
NAME CHAR 64
DESCRIPT CHAR 50
VALUE INTEGER 4
STATUS INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

3. EnumPoints - enumerated types including Boolean type.

COLUMN NAME VALUE TYPE SIZE
NAME CHAR 64
DESCRIPT CHAR 50
VALUE INTEGER 4
STATUS INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

4. TimePoints - absolute time values.

COLUMN NAME VALUE TYPE SIZE
NAME CHAR 64
DESCRIPT CHAR 50
VALUE TIMESTAMP   
STATUS INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

5. TextPoints

COLUMN NAME VALUE TYPE SIZE
NAME CHAR 64
DESCRIPT CHAR 50
VALUE CHAR 254
STATUS INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

Variables of the types Value array and Structured variable are in separated tables. Table name is derived from a name of the variable so that the dot character "." is substituted by the underscore character "_" in the name.

Each object of the Value array type creates a table of the following format:

COLUMN NAME VALUE TYPE SIZE
TIME TIMESTAMP  
VALUE DOUBLE 8
STATUS INTEGER 4
ROW_ID INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4

Each object of Structured variable type creates a table of the format corresponding to a form of the structure variable. In addition, ROW_ID column, determining an order number - structured variable row, is added to this table.

Historical data


The variables of Historical value type create separated tables. Table name is derived from the name of the historical variable so that the dot character "." is substituted by the underscore character "_" in the name.

Each variable of Historical value type creates a table of the following format:

COLUMN NAME VALUE TYPE SIZE
TIME TIMESTAMP  
VALUE DOUBLE 8
STATUS INTEGER 4
STEP INTEGER 4
WEAK INTEGER 4
DEFAULT INTEGER 4
LIMITS INTEGER 4
FLAGS INTEGER 4
ARCH_FLAGS INTEGER 4

There is implemented the table ArchivValues which enables to get values of several archive objects with the same time. By a selection from this table, it is possible to enter several names of archive objects within one command.

For example:

SELECT TIME,VALUE01,STATUS01,VALUE02,STATUS02 FROM ArchivValues WHERE TIME >{ts '2000-04-11 10:00:00'} and TIME <{ts '2000-04-11 12:00:00'} and NAME01="H.AAA1" and NAME02="H.AAA2" and STEP=60

The structure of the table ArchivValues:

COLUMN NAME VALUE TYPE SIZE
TIME TIMESTAMP  
STEP INTEGER 4
NAME01 CHAR 64
VALUE01 DOUBLE 8
STATUS01 INTEGER 4
WEAK01 INTEGER 4
DEFAULT01 INTEGER 4
LIMITS01 INTEGER 4
FLAGS01 INTEGER 4
ARCH_FLAGS01 INTEGER 4
NAME02 CHAR 64
VALUE02 DOUBLE 8
STATUS02 INTEGER 4
WEAK02 INTEGER 4
DEFAULT02 INTEGER 4
LIMITS02 INTEGER 4
FLAGS02 INTEGER 4
ARCH_FLAGS02 INTEGER 4
...    
NAMEn CHAR 64
VALUEn DOUBLE 8
STATUSn INTEGER 4
WEAKn INTEGER 4
DEFAULTn INTEGER 4
LIMITSn INTEGER 4
FLAGSn INTEGER 4
ARCH_FLAGSn INTEGER 4

Where n is at most 12.

ESL RPC procedure call


D2000 ODBC Driver enables also ESL RPC procedure call which corresponds to CALL action. There are created the special tables, which names are derived from D2000 EventHandler name, on which the procedure is to be done, the object of event type and RPC procedure name. They are joined by the character "^" (e.g. SELF_EVH^E_event^proc). The dot characters "." in the name are replaced by an underscore character "_". The tables without Event handler process name in their name (e.g. E_event^proc) are intended for a broadcast RPC procedure call.
The columns are named according to the procedure parameters. RECORD type parameters are represented by columns which are composed by the parameter name and structure column name (parameter^column). These tables also contain "ROW_ID" column. The dot character "." is substituted by the underscore character "_" in the parameter name. The RPC procedure tables contain the columns "$async" and "$instanceId".

The procedure call types:

  • synchronous - the column "$async" may not be used in SELECT part,
  • asynchronous - the only column "$async" may be used in SELECT part,
  • broadcast - RPC table without Event handler name may be used.

When the procedure call is addressed directly to some instance, WHERE part have to contain the column $instanceId".

A general syntax of RPC procedure call:

SELECT $async | param1, param2, param3, ...
            FROM [proces_EVH^]E_event^proc
            [WHERE param3 = x AND param4 = y AND ... [$instanceId = id]]


Examples of RPC procedure call via ESL and their ODBC equivalent:

synchronous call: CALL E.event MyProc(_param1, 2) SYNC ON SELF.EVH
SELECT _param1 FROM SELF_EVH^E_event^MyProc WHERE _param2 = 2
asynchronous call: CALL E.event MyProc(1, 2) ASYNC ON SELF.EVH
SELECT $async FROM SELF_EVH^E_event^MyProc WHERE _param1 =1 AND _param2 = 2

WHERE part may contain only a value assignment to the parameters.
SELECT output will contain as many rows as RECORD parameter with the most rows or 1 row, if the procedure has only the unstructured types of parameters. If some exception occurs while the procedure is done, SQL query runtime will fail. The result of the asynchronous procedure call is unknown, therefore this query does not return any data.

Limitations


The limits for the command SELECT:

  1. A SELECT command can contain just one table.
  2. Sorting is enabled only according to value of one column (ORDER BY).
  3. Selecting an historical value must contain a time interval, e.g. 

SELECT TIME,VALUE,STATUS FROM H_NAME WHERE (TIME >"10-04-2000" AND TIME <"12-04-2000 10:00").

It can contain a definition of required time step in seconds, e.g.

SELECT TIME,VALUE,STATUS FROM H_NAME WHERE (TIME >"10-04-2000" AND TIME <"12-04-2000 10:00") AND STEP=60.

The syntax for entering an absolute time is either "dd-mm-rrrr [hh[:mi[:ss[.mss]]]]" or {ts '2000-04-11 10:00:00'}.


The limits for RPC procedure call:

  1. RPC procedures:
    • without any parameters,
    • containing ALIAS parameters,
    • containing IN parameters of RECORD type
    cannot be called.
  2. The column $instanceId of RPC tables can be only in WHERE part of the SQL query.
  3. The column $async of RPC tables can be only in SELECT part of the SQL query and cannot be combined with other column.
  4. The columns of RPC tables, representing the columns of RECORD parameters, cannot be used in WHERE part of the SQL query.
  5. The columns of RPC tables, representing IN parameters, cannot be used in SELECT part of the SQL query.
  6. Neither ORDER BY clause nor the aggregate functions (count, avg, max, ...) are supported while RPC procedure is called.

Description of columns with status information


STATUS - value is valid if STATUS = 1
WEAK - value is Weak if WEAK = 1
DEFAULT - value is in Default status if DEFAULT = 1
LIMITS - the column can contain the following values:

InLimit = 0 , VL_Limit = 1 , L_Limit = 2 , H_Limit = 3 , VH_Limit = 4 , LimitsProblem = 5

FLAGS - the column gets values of Extended flags (in bitsets):

BF_A = 1, BF_B = 2, BF_C = 4, BF_D = 8, BF_E = 16, BF_F = 32, BF_G = 64, BF_H = 128, BF_I = 256, BF_J = 512,

BF_K = 1024, BF_L = 2048, BF_M = 4096, BF_N = 8192, BF_O = 16384, BF_P = 32768
ARCH_FLAGS - the column gets archive flags (as a sum of these constants).
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