FB_EcCoeSdoRead

FB_EcCoeSdoRead 1:

The function block FB_EcCoeSdoRead allows data to be read from an object directory of an EtherCAT slave via SDO (Service Data Object) access. This requires the slave to have a mailbox and to support the “CANopen over EtherCAT” (CoE) protocol. The nSubIndex and nIndex parameters allow the object that is to be read to be selected. The function block FB_EcCoeSdoReadEx must be used for access to the complete parameter, including subelements.

Inputs

VAR_INPUT
    sNetId     : T_AmsNetId; 
    nSlaveAddr : UINT; 
    nSubIndex  : BYTE; 
    nIndex     : WORD;
    pDstBuf    : PVOID; 
    cbBufLen   : UDINT; 
    bExecute   : BOOL;
    tTimeout   : TIME := DEFAULT_ADS_TIMEOUT; 
END_VAR

Name	Type	Description
sNetId	T_AmsNetId	String containing the AMS network ID of the EtherCAT master device. (Type: T_AmsNetId)
nSlaveAddr	UINT	Fixed address of the EtherCAT slave to which the SDO upload command should be sent.
nSubIndex	BYTE	Subindex of the object that is to be read.
nIndex	WORD	Index of the object that is to be read.
pDstBuf	PVOID	Address (pointer) to the receive buffer.
cbBufLen	UDINT	Maximum available buffer size (in bytes) for the data to be read.
bExecute	BOOL	The function block is activated by a positive edge at this input.
tTimeout	TIME	Maximum time allowed for the execution of the function block.

Outputs

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

Name	Type	Description
bBusy	BOOL	This output is set when the function block is activated, and remains set until feedback is received.
bError	BOOL	This output is set after the bBusy output has been reset when an error occurs in the transmission of the command.
nErrId	UDINT	Supplies the ADS error code associated with the most recently executed command if the bError output is set.
cbRead	UDINT	Number of successfully read data bytes

Example of an implementation in ST:

PROGRAM TEST_SdoRead
VAR
    fbSdoRead  : FB_EcCoESdoRead;
    sNetId     : T_AmsNetId := '172.16.2.131.2.1';
    bExecute   : BOOL;
    nSlaveAddr : UINT := 1006;
    nIndex     : WORD := 16#1018;
    nSubIndex  : BYTE :=1;
    vendorId   : UDINT;
    bError     : BOOL;
    nErrId     : UDINT;
END_VAR

fbSdoRead(sNetId:= sNetId,nSlaveAddr :=nSlaveAddr, nIndex:=nIndex, nSubIndex :=nSubIndex, pDstBuf:= ADR(vendorId), cbBufLen:=SIZEOF(vendorId),bExecute:=bExecute);
bError:=fbSdoRead.bError;
nErrId:=fbSdoRead.nErrId;

Prerequisites

Development environment	Target platform	PLC libraries to include
TwinCAT v3.1.0	PC or CX (x86, x64, Arm^®)	Tc2_EtherCAT