ADSREAD

The function block executes an ADS read command to request data from an ADS device.

	Outdated response data After a disconnection, the old response data is output when the connection is reconnected. To prevent this, be careful not to use the same ADS-Read instance for multiple targets.

Inputs

VAR_INPUT
    NETID     : T_AmsNetId;
    PORT      : T_AmsPort;
    IDXGRP    : UDINT;
    IDXOFFS   : UDINT;
    LEN       : UDINT;
    DESTADDR  : PVOID;
    READ      : BOOL;
    TMOUT     : TIME := DEFAULT_ADS_TIMEOUT;
END_VAR

Name	Type	Description
NETID	T_Ams NetId	String containing the AMS network ID of the target device to which the ADS command is addressed (type: T_AmsNetId).
PORT	T_Ams Port	Port number of the ADS device (type: T_AmsPort)
IDXGRP	UDINT	Index group number (32-bit, unsigned) of the requested ADS service. This value is to be found in the ADS table of the addressed device.
IDXOFFS	UDINT	Index offset number (32-bit, unsigned) of the requested ADS service. This value is to be found in the ADS table of the addressed device.
LEN	UDINT	Number of data to be read in bytes
DESTADDR	PVOID	Address of the buffer that is to receive the read data. The programmer is responsible for dimensioning the buffer such that it can accommodate LEN bytes. The buffer can be a single variable, an array or a structure, whose address can be found with the ADR operator.
READ	BOOL	The ADS command is triggered by a rising edge at this input.
TMOUT	TIME	Indicates the time before the function is canceled.

Outputs

VAR_OUTPUT
    BUSY    : BOOL;
    ERR     : BOOL;
    ERRID   : UDINT;
END_VAR

Name	Type	Description
BUSY	BOOL	This output remains TRUE until the function block has executed a command, but at the longest for the duration supplied to the Timeout input. No new commands are accepted at the inputs as long as BUSY = TRUE. Note that it is not the execution of the service but its acceptance whose time is monitored.
ERR	BOOL	This output is switched to TRUE as soon as an error occurs during the execution of a command. The command-specific error code is contained in ERRID. If the function block has a timeout error, ERR is TRUE and ERRID is 1861 (hexadecimal 0x745). Is reset to FALSE by the execution of a command at the inputs.
ERRID	UDINT	ADS error code or command-specific error code of the last executed command. Is reset to 0 by the execution of a command at the inputs.

Example of calling the block in ST:

Example with AdsRead function block

Example of calling the block in FBD:

ADSREAD 5:

Here the error status of axis no. 6, as an element with a size of 4 bytes, is interrogated and written into the dataArr buffer. The IDXGRP 00004006 (hex) and the IDXOFFS 00000001 (hex) can be found in the NC-ADS documentation.

Requirements

Development environment	Target system type	PLC libraries to include (Category group)
TwinCAT v3.1.0	PC or CX (x86, x64, ARM)	Tc2_System (System)