Overview

Not all those function blocks and functions that are often needed in PLC applications are standardized in IEC61131-3. The Tc2_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.

General function blocks

Name	Description
DRAND	Random number generator
FB_IecCriticalSection	Critical sections should be made mutually exclusive
FB_SetLedColor_BAPI	Switches the user LED to PCs and Émbedded PCs with BIOS API support
GETCURTASKINDEX	Determines the index of the current task

ADS function blocks

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

Expanded ADS function blocks

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

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

EventLogger function blocks

The TwinCAT EventLogger has the task of managing all messages (events) appearing in the TwinCAT system; to forward them and where necessary to write them into the TwinCAT log file.

Name	Description
ADSLOGEVENT	Sending and acknowledging TwinCAT EventLogger messages.
ADSCLEAREVENTS	Sending and acknowledging TwinCAT EventLogger messages.
FB_SimpleAdsLogEvent	Sending and acknowledging TwinCAT EventLogger messages.

	TwinCAT EventLogger vs. TwinCAT 3 EventLogger The TwinCAT EventLogger was replaced by the successor TwinCAT 3 EventLogger. The older TwinCAT EventLogger is supported by TwinCAT 3 up to version 3.1.4024. Newer TwinCAT versions (>= 3.1.4026.0) only support the newer TwinCAT 3 EventLogger. PLC function blocks for this can be found in the PLC library Tc3_EventLogger.

IEC steps / SFC flags function blocks

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

Name	Description
AnalyzeExpression	Required if SFC flags are used
AnalyzeEspressionTable	Required if SFC flags are used
AnalyzeExpressionCombined	Required if SFC flags are used
AppendErrorString	Required if SFC flags are used in order to format strings with error description
SFCActionControl	Enables the use of IEC steps

Watchdog function blocks

Name	Description
FB_PcWatchdog	Activates or deactivates the PC watchdog Only available on IPCs with the following mainboards: IP-4GVI63, CB1050, CB2050, CB3050, CB1051, CB2051, CB3051
FB_PcWatchdog_BAPI	Activates or deactivates the PC watchdog Only available on IPCs with the following mainboards: CBxx63 with a BIOS version >=0.44

Name

Description

FB_PcWatchdog

Activates or deactivates the PC watchdog

Only available on IPCs with the following mainboards: IP-4GVI63, CB1050, CB2050, CB3050, CB1051, CB2051, CB3051

FB_PcWatchdog_BAPI

Activates or deactivates the PC watchdog

Only available on IPCs with the following mainboards: CBxx63 with a BIOS version >=0.44

Time function blocks

Name	Description
GETCPUCOUNTER	Read the CPU cycle counter
GETCPUACCOUNT	Read the PLC task cycle counter

General functions

Name	Description
F_CheckMemoryArea	Returns information about the memory area in which the requested variable with the specified size is located
F_CmpLibVersion	Compares an existing library with the required version
F_CreateIPv4Addr	Converts individual IPv4 address bytes to a string
F_ScanIPv4AddrIds	Converts an IPv4 address string to individual address bytes
F_GetMappingPartner	Returns the object ID of the partner side of the mapping
F_GetMappingStatus	Returns the current mapping status of a PLC variable
F_GetStructMemberAlignment	Reads information about the memory alignment used
F_SplitPathName	Splits the path name into four individual components
SETBIT32	Sets a bit in a DWORD
CSETBIT32	Setting/resetting of a bit in a DWORD
GETBIT32	Reads a bit from a DWORD
CLEARBIT32	Clears a bit in a DWORD
GETCURTASTINDEXEX	Determining the task index
LPTSIGNAL	Outputs a signal on one of the parallel port pins
TestAndSet	Setting and checking a flag without option to interrupt it

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

Character functions

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

I/O port access

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

Memory functions

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

Notice

System crash or access to forbidden memory areas

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
MEMMOVE	Copies the values from overlapping memory areas
MEMSET	Sets the variables in a memory area to a particular value

Time functions

Name	Description
F_GetSystemTime	Read the operating system time stamp
F_GetTaskTime	Read the target start time of the task