Overview

Not all those function blocks and functions that are often needed in PLC applications are standardized in IEC61131-3. The system library contains such functions and function blocks for the TwinCAT system which do not belong to the standard scope of IEC61131-3, and which are therefore manufacturer-specific.

Function blocks

ADS function blocks

Name	Description
ADSREAD	Reading data via ADS.
ADSWRITE	Writing data via ADS.
ADSRDWRT	Reading and writing data via ADS.
ADSRDSTATE	Read the state of a device via ADS.
ADSWRTCTL	Write control words to a device via ADS.
ADSRDDEVINFO	Read device information via ADS.
ADSREADEX	Reading data via ADS and returning the number of read data bytes.
ADSRDWRTEX	Writing data via ADS and reaturning the number of read data bytes

Extended ADS function blocks

Name	Description
ADSREADIND	ADSREAD-Indication.
ADSWRITEIND	ADSWRITE-Indication
ADSRDWRTIND	ADSRDWRT-Indication
ADSREADRES	ADSREAD-Response
ADSWRITERES	ADSWRITE-Response
ADSRDWRTRES	ADSRDWRT-Response

General function blocks

Name	Description
DRAND	Random number generator.
GETCURTASKINDEX	Determines the index of the current task.

Time function blocks

Name	Description
GETSYSTEMTIME	Read the operating system time stamp.
GETTASKTIME	Read the target start time of the task.
GETCPUCOUNTER	Read the CPU cycle counter.
GETCPUACCOUNT	Read the PLC task cycle counter.

Watchdog function blocks

Name	Description
FB_PcWatchdog	Activate or Deactivate the PC Watchdog. Is only available on IPCs with the mainboards: IP-4GVI63, CB1050, CB2050, CB3050, CB1051, CB2051, CB3051 !

F unction blocks for data access

The function blocks can be used to process files from the PLC locally on the PC. The TwinCAT target system is identified by the AMS network address. This mechanism makes it possible, amongst other things, to store or to edit files on other TwinCAT systems in the network. Access to files consists of three sequential phases:

Opening the file.
Read or write access to the opened file.
Closing the file.

Opening the file has the purpose of establishing a temporary connection between the external file, whose name is all that initially is known, and the running program. Closing the file has the purpose of indicating the end of the processing and placing it in a defined output state for processing by other programs.

Name	Description
FB_FileOpen	Open a file.
FB_FileClose	Close a file.
FB_FileWrite	Write to a file.
FB_FileRead	Read from a file.
FB_FileSeek	Move the file pointer.
FB_FileTell	Get the file pointer position.
FB_FilePuts	Put string to a file.
FB_FileGets	Get string from a file.
FB_EOF	Check the end of file.
FB_FileDelete	Delete a file.
FB_FileRename	Rename a file.
FB_CreateDir	Create new directory.
FB_RemoveDir	Remove directory.

TwinCAT 2.7 function blocks for data access

These function blocks are contained only for compatibility reasons in the library and should not not be used in new projects.

Name	Description
FILEOPEN	Open a file.
FILECLOSE	Close a file.
FILEWRITE	Write to a file.
FILEREAD	Read from a file.
FILESEEK	Move the file pointer.

IEC SFC functions

These functions / function blocks are required to use IEC steps or SFC flags in SFC programs /projects.

Name	Description
SFCActionControl	Enables the using of IEC steps.
AnalyzeExpression AnalyzeExpressionCombined	Is required for using SFC flags.
AppendErrorString	Is required for using SFC flags, to format strings with error description.

Event logger function blocks

The TwinCAT Eventlogger manages all occurring messages (events) in the TwinCAT System. It transfers the data and writes them into the TwinCAT log file.

Name	Description
ADSLOGEVENT	Sending and acknowledgement of messages to the TwinCAT Eventlogger.
ADSCLEAREVENTS	Sending and acknowledgement of messages to the TwinCAT Eventlogger.

For further information see the TwinCAT Event Logger documentation.

Functions

General functions

Name	Description
F_SplitPathName	Splits a path name into components.
F_CreateIPv4Addr	Converts address bytes to IPv4 address string.
F_ScanIPv4AddrIds	Converts IPv4 address string to address bytes..
SETBIT32	Sets a bit in a DWORD.
CSETBIT32	Sets/resets a bit in a DWORD.
GETBIT32	Reads a bit from a DWORD.
CLEARBIT32	Clears a bit in a DWORD.
LPTSIGNAL	Outputs a signal on one of the parallel port pins.
F_GetStructMemberAlignment	Reads data struct member alignment information.
F_GetVersionTcSystem	Returns the library version info

I/O port access

Name	Description
F_IOPortRead	Reads from I/O Port
F_IOPortWrite	Writes to I/O Port

ADS functions

Functions are described below which, with the aid of the ADS interface makes some of the functions of the Windows-NT operating system (such as the output of message boxes) accessible through PLC calls.

Name	Description
ADSLOGDINT	Log a DINT variable into NT Eventlog and/or Messagebox.
ADSLOGLREAL	Log a (L)REAL variable into NT Eventlog and/or Messagebox.
ADSLOGSTR	Log a STRING variable into NT Eventlog and/or Messagebox.
F_CreateAmsNetId	Creates AmsNetId string
F_ScanAmsNetIds	Converts AmsNetId string to array of address bytes

MEMORY functions

Number of functions which provide direct access to memory areas in the PLC runtime system.

Comment

The fact that these functions allow direct access to the physical memory means that special care is called for in applying them! Incorrect parameter values can result in a system crash, or in access to forbidden memory areas.

Name	Description
MEMCMP	Compares the values of variables in two memory areas
MEMCPY	Copies the values of variables from one memory area to another
MEMSET	Sets the variables in a memory area to a particular value
MEMMOVE	Copies the values from overlapping memory areas

Character functions

Name	Description
F_ToASC	Converts string character to ASCII number
F_ToCHR	Converts ASCII number to string character