FB_EcPhysicalReadCmd

FB_EcPhysicalReadCmd 1:

The function block FB_EcPhysicalReadCmd can be used to send an EtherCAT read command (FPRD, APRD, BRD) to a particular EtherCAT slave or to all EtherCAT slaves. This command can be used by the PLC to read a register or the DPRAM of the EtherCAT slave controller.

Inputs

VAR_INPUT
    sNetId   : T_AmsNetId; 
    adp      : UINT;
    ado      : UINT;
    len      : UDINT;
    eType    : E_EcAdressingType := eAdressingType_Fixed;
    pDstBuf  : PVOID;
    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)
adp	UINT	This value determines which EtherCAT slave is to be addressed with this command. The meaning of this value depends on the addressing mode selected with eType. (See adp value)
ado	UINT	Physical memory (DPRAM) or register to be read.
len	UDINT	Number of bytes to be read.
eType	E_EcAdressingType	Different EtherCAT commands are sent, depending on value of eType. (See eType)
pDstBuf	PVOID	The address (pointer) of the receive buffer.
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.

adp value

This value determines which EtherCAT slave is to be addressed with this command. The meaning of this value depends on the addressing mode selected with eType:

eType	Description
eAdressingType_Fixed	The slave is addressed by means of its configured EtherCAT address. These EtherCAT addresses can be read via the function block FB_EcGetAllSlaveAddr.
eAdressingType_AutoInc	The slave is addressed based on its position in the ring. The first device has the address 0 (adp=0); adp is decremented by one for all subsequent slaves: 1. Slave adp = 0 2. Slave adp = 16#ffff (-1) 3. Slave adp = 16#fffe(-2) 4. Slave adp = 16#fffd(-3) etc.
eAdressingType_BroadCAST	All slaves are addressed by this command. adp can be set to 0.

eType

Different EtherCAT commands are sent, depending on value of eType:

eType	Command
eAdressingType_Fixed	Configured Address Physical Read ( FPRD)
eAdressingType_AutoInc	Auto Increment Physical Read ( APRD)
eAdressingType_BroadCAST	Broadcast Read ( BRD)

The individual commands differ in terms of addressing mode (see adp).

Outputs

VAR_OUTPUT
    bBusy  : BOOL;
    bError : BOOL;
    nErrId : UDINT;
    wkc    : UINT; 
END_VAR

Name	Type	Description
bBusy	BOOL	This output is set when the function block is activated, and remains set until a 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.
wkc	UINT	The working counter is incremented by each EtherCAT slave that has processed this command successfully. If only one EtherCAT slave was addressed by this command, this value should therefore be 1.

Example of an implementation in ST:

PROGRAM TEST_PhysicalReadCmd
VAR
    fbReadCmd : FB_EcPhysicalReadCmd;
    bExecute  : BOOL;
    value     : UINT;
    adp       : UINT:=16#3E9;
    ado       : UINT:=16#1100;
    eType     : E_EcAdressingType := eAdressingType_Fixed;
    sNetId    : T_AmsNetId:='192.168.1.5.3.1';
    wkc       : UINT;
    bError    : BOOL;
    nErrId    : UDINT; 
END_VAR

fbReadCmd (sNetId:=sNetID, ado:=ado, adp:=adp, eType:=eType, LEN := SIZEOF(value), pDstBuf:=ADR(value), bExecute:=bExecute);
wkc := fbReadCmd.wkc;
bError:= fbReadCmd.bError;
nErrId:= fbReadCmd.nErrId;

Requirements

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