eipReadAttr

PLCopen motion icon

Function Block - Sends an explicit message (UCMM) to an EtherNet/IP adapter to read a single CIP attribute.

The servers (adapters) accessed by this block must be configured in the EtherNet/IP Scanner fieldbus configuration.
Only one explicit message (read or write) can be sent at one time to the same server.
- If another message is pending you receive the error report 3 (busy) after calling the block to start a new exchange.
Consider SerializeIn and SerializeOut functions for extracting data from the read buffer.

Inputs

Input	Data Type and hyperlink for F/FB table header cellsData TypeSee Data Types.	Range	Unit	Default	Description
Snd	BOOL	FALSE, TRUE	N/A	No default	A rising edge on this input starts the exchange. The DONE output signals the end of exchange.
SrvIP	STRING	No range	N/A	No default	IP address of the server (adapter) (e.g., configured in the EtherNet/IP Scanner configuration).
Class	UINT	No range	N/A	No default	Class identifier of the CIP object.
Inst	UINT	1 to 65535	N/A	No default	Instance identifier of the CIP object.
Attr	UINT	No range	N/A	No default	Identifier of the CIP attribute.
Data	USINT[ ]	Dimension: The number of bytes to read. Data: No range	N/A	No default	Buffer where to store the received data. If the actual attribute length is greater than the size of this array, the value is truncated when read.

Outputs

Output	Data Type and hyperlink for F/FB table header cellsData TypeSee Data Types.	Range	Unit	Description
Done	BOOL	FALSE, TRUE	N/A	This output is TRUE during one cycle when the exchange is finished, whether the exchange succeeded or failed. Warning: This output can be TRUE just after the call to block when starting a new exchange in case of invalid parameters.
RcvSize	UINT	0 to 450	N/A	Actual size of the CIP attribute answered by the server. If this size is greater than the size of the DATA input array, it indicates the value was truncated.
Err	UINT	No range	N/A	Main error report. Can be one of these values: 0 = No error. 1 = Invalid input arguments. 2 = System is busy (see remarks). 3 = Timeout waiting for the answer (the timeout value is 3 seconds). 4 = UCMM error was returned by the server others = internal errors (reserved for technical support).
EmErr	UINT	No range	N/A	In case of a UCMM error, this is the CIP general status error code.
EmErrExt	UINT	No range	N/A	In case of a UCMM error, this is the CIP extended status error code.

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

Not available.

ST Language Example

// used variables
// Inst_eipReadAttr : eipReadAttr ;
// bRead : BOOL ; (* request for READ *)
// DataRead : ARRAY [0 .. 15] OF USINT ; (* read data *)
// Server identification and CIP things
#define SRVIP '192.168.33.21'
#define CLASSID UINT#100
#define INSTID_READ UINT#1
#define ATTRID UINT#3
/////////////////////////////////////////////////////////////////////////////////////////
// requested READ command
if bRead then
    Inst_eipReadAttr (bRead, SRVIP, CLASSID, INSTID_READ, ATTRID, DataRead);
end_if;
// READ answer here ?
if Inst_eipReadAttr.Done then
// check answer - if OK answered data is in DataRead array
    if Inst_eipReadAttr.Err = 0 then
        printf ('READ ok - size = %lu bytes',
            any_to_dint (Inst_eipReadAttr.RcvSize));
    else
        printf ('READ Error %lu (UCMM Error %lu, %lu)',
            any_to_dint (Inst_eipReadAttr.Err),
            any_to_dint (Inst_eipReadAttr.EmErr),
            any_to_dint (Inst_eipReadAttr.EmErrExt));
    end_if;
// reset READ command and block input
    Inst_eipReadAttr (false, SRVIP, CLASSID, INSTID_READ, ATTRID, DataRead);
    bRead := false;
end_if;