FB_RegQueryValue

The system registry is a hierarchically structured tree. A node in the tree is referred to as a key. Each key may contain subkeys and data values. The function block "FB_RegQueryValue" can be used to read individual system registry values from the branch with the predefined handle HKEY_LOCAL_MACHINE. If successful cbData data bytes are copied into the buffer with the address pData. The function block can be used to read any value types (e.g. REG_DWORD, REG_SZ) or binary data with unlimited byte length (REG_BINARY).

Comment:

The sSubKey and sValueName strings may not be empty!

	HKEY_LOCAL_MACHINE\SOFTWARE\ for 64 bit operating systems In a 64 bit Windows operating system all registry entries of and for 32 bit applications are not stored under HKEY_LOCAL_MACHINE\SOFTWARE\ but under HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\. The function blocks FB_RegQueryValue and FB_RegSetValue work automatically below the WOW6432Node folder like any 32 bit application when a registry entry below the SOFTWARE folder is selected. The redirection is performed automatically by the operating system.

Inputs

VAR_INPUT
    sNetId    : T_AmsNetId; 
    sSubKey   : T_MaxString;
    sValName  : T_MaxString;
    cbData    : UDINT;
    pData     : POINTER TO BYTE;
    bExecute  : BOOL;
    tTimeOut  : TIME := DEFAULT_ADS_TIMEOUT;
END_VAR

Name	Type	Description
sNetId	T_AmsNetID	A string with the network address of the TwinCAT computer whose system registry is to be read can be specified here. For the local computer an empty string may be specified.
sSubKey	T_MaxString	String with the subkey name
sValName	T_MaxString	String with the value name
cbData	UDINT	The number of value data bytes to be read.
pData	BYTE	Address of a data buffer/variable into which the value data are to be copied. The address can be determined with the ADR operator. The programmer is responsible for dimensioning the data buffer such that it can accommodate cbData data bytes.
bExecute	BOOL	The function block is enabled by a positive edge at this input.
tTimeout	TIME	States the length of the timeout that may not be exceeded by execution of the ADS command.

Outputs

VAR_OUTPUT
    bBusy  : BOOL;
    bError : BOOL;
    nErrId : UDINT;
    cbRead : UDINT;
END_VAR

Name	Type	Description
bBusy	BOOL	When the function block is enabled, this output is set and remains set until a feedback is received.
bError	BOOL	If an error occurs during the transmission of the command, this output is set after the bBusy output is reset.
nErrId	UDINT	Returns the ADS error number or the command-specific error code (table) when the bError output is set.

Error Codes	Error description
0x00	No error
0x01/	The key with the name sSubKey could not be opened/found.
0x02/	The key value with the name sValName could not be opened/found.

Name	Type	Description
cbRead	UDINT	The number of value data bytes successfully read.

Examples:

The values AxisID and LogFilePath are to be read from the system registry.

PROGRAM MAIN
VAR
    fbRegQueryValue   : FB_RegQueryValue;
    bRead             : BOOL;
    bBusy             : BOOL;
    bError            : BOOL;
    nErrId            : UDINT;
    cbRead            : UDINT;
    sValData          : STRING;
    nAxisID           : DWORD;
END_VAR

Read REG_DWORD-Value:

FB_RegQueryValue 6:

The value 0x22 of the registry was read in the PLC variable nAxisId .

Read REG_SZ-Value :

FB_RegQueryValue 7:

The string 'c:\MyProject\Log' of the registry was read in the PLC variable sValData.

Requirements

Development environment	Target platform	PLC libraries to be integrated (category group)
TwinCAT v3.1.0	PC or CX (WES7/Win7/Win10: TC RT x86/x64, WEC6/7: TC RT x86, WEC7: TC CE7 ARMV7, TC/BSD: TC RT x64, TC OS ARMT2)	Tc2_Utilities (System)