Logging of one PLC variable with FB_DBWrite
Download: "Example to log a PLC variable with FB_DBWrite" sample3.zip
In this example the log of a PLC variable out of the PLC into a database will be demonstrated. The functionalities of each write-modes are shown.
Used database type | MS SQL |
Compatible database type | ASCII, MS SQL, MS Compact SQL, MS Access, MySQL, PostgreSQL, DB2, Oracle, InterBase/Firebird |
Used function blocks | FB_DBWrite |
Integrated libraries | "TcDatabase.lib", "TcSystem.lib","TcBase.lib","TcStandard.lib" |
Download data list | FB_DBWrite_Sample.pro, CurrentConfigDataBase.xml, SQLQuery.sql |
To use this example, you need to adjust the server name and the authentication in the XML-configuration data.
Furthermore, you need to keep in mind that no "TestDB" database is available before you carry out the SQLQuery.sql Script.
Configuration example:
With the help of the variable "eWriteMode" you can set with which write-mode it should be logged.
With a rising edge at the variable "bSTART" the write operation can be started.
Table:
- ADS_TO_DB_APPEND => eWriteAppend -> "tbl_Append"
- ADS_TO_DB_UPDATE => eWriteUpdate -> "tbl_Update"
- ADS_TO_DB_RINGBUFFER => eWriteRingBuffer -> "tbl_RingBuffer"
Used table structure for each table
Column name | Data type | Zero allowed | Property |
|---|---|---|---|
ID | bigint | no | IDENTITY(1,1) |
Timestamp | datetime | no |
|
Name | ntext | no |
|
Value | float | no |
|
Variable declaration
PROGRAM MAIN
VAR(*Test symbol which will be logged into the different database tables*)
lrTestValueVar : LREAL := 123.456;
eState : E_SampleState := eIdle;
R_TRIG1: R_TRIG;
(*With a rising edge at bStart the FB_DBWrite block will be start once*)
bSTART: BOOL;
(*With eWriteMode you can select which FB_DBWrite block will be used*)
eWriteMode: E_SampleState := eWriteAppend;
FB_DBWrite_Append: FB_DBWrite;
FB_DBWrite_Update: FB_DBWrite;
FB_DBWrite_RingBuffer: FB_DBWrite;
(*Status outputs from the three FB_DBWrite blocks*)
bBusy: BOOL;
bErr: BOOL;
bErrid: UDINT;
stSqlstate: ST_DBSQLError;
END_VAR
Enum E_SampleState
TYPE E_SampleState :(
eIdle := 0,
eWriteAppend := 1,
eWriteUpdate := 2,
eWriteRingBuffer := 3
);
END_TYPE
PLC Program
CASE eState OF
eIdle :
R_TRIG1(CLK:=bSTART);
IF R_TRIG1.Q THEN
lrTestValueVar := lrTestValueVar + 1;
eState := eWriteMode;
bSTART := FALSE;
END_IF(*Add a new record to the table tbl_Append*)
eWriteAppend :
FB_DBWrite_Append(
sNetID:= ,
hDBID:= 1,
hAdsID:= 1,
sVarName:= 'MAIN.lrTestValueVar',
nIGroup:= ,
nIOffset:= ,
nVarSize:= ,
sVarType:= ,
sDBVarName:= 'lrTestValueVar',
eDBWriteMode:= eDBWriteMode_Append,
tRingBufferTime:= ,
nRingBufferCount:= ,
bExecute:= TRUE,
tTimeout:= T#15s,
bBusy=> bBusy,
bError=> bErr,
nErrID=> bErrid,
sSQLState=> stSqlstate);
IF NOT bBusy THEN
FB_DBWrite_Append(bExecute := FALSE);
eState := eIdle;
END_IF(*Add a new record to the table tbl_Update if it not exist else the existing record will be updated*)
eWriteUpdate :
FB_DBWrite_Update(
sNetID:= ,
hDBID:= 2,
hAdsID:= 1,
sVarName:= 'MAIN.lrTestValueVar',
nIGroup:= ,
nIOffset:= ,
nVarSize:= ,
sVarType:= ,
sDBVarName:= 'lrTestValueVar',
eDBWriteMode:= eDBWriteMode_Update,
tRingBufferTime:= ,
nRingBufferCount:= ,
bExecute:= TRUE,
tTimeout:= T#15s,
bBusy=> bBusy,
bError=> bErr,
nErrID=> bErrid,
sSQLState=> stSqlstate);
IF NOT bBusy THEN
FB_DBWrite_Update(bExecute := FALSE);
eState := eIdle;
END_IF(*Add a new record to the table tbl_RingBuffer. If the maximum count is reached the records will be deleted in a FIFO process*)
eWriteRingBuffer :
FB_DBWrite_RingBuffer(
sNetID:= ,
hDBID:= 3,
hAdsID:= 1,
sVarName:= 'MAIN.lrTestValueVar',
nIGroup:= ,
nIOffset:= ,
nVarSize:= ,
sVarType:= ,
sDBVarName:= 'lrTestValueVar',
eDBWriteMode:= eDBWriteMode_RingBuffer_Count,
tRingBufferTime:= ,
nRingBufferCount:= 10,
bExecute:= TRUE,
tTimeout:= T#15s,
bBusy=> bBusy,
bError=> bErr,
nErrID=> bErrid,
sSQLState=> stSqlstate);
IF NOT bBusy THEN
FB_DBWrite_RingBuffer(bExecute := FALSE);
eState := eIdle;
END_IFEND_CASE
 | All the Microsoft SQL Compact databases that are declared in the XML configuration file must exist. They are not generated automatically. |