Function BlockeipReadAttrPLCopen motion icon

This function block sends an explicit message (UCMM) to an Ethernet/IP adapter, for reading a single CIPClosed"Common Industrial Protocol " The Common Industrial Protocol allows complete integration of control with information, multiple CIP Networks, and Internet technologies attribute.

Inputs

Parameter Type Description
Snd BOOL A rising edgeClosedA rising edge is the transition of a digital signal from low to high. It is also called positive edge on this input start the exchange. The DONE output will signal the end of exchange.
SrvIP STRING IP address of the server (adapter) such as configured in the "Ethernet/IP Scanner" configuration.
Class UINT Class identifier of the CIP object.
Inst UINT Instance identifier of the CIP object.
Attr UINT Identifier of the CIP attribute.
Data array of UINT Buffer where to store the received data. If the actual attribute length is greater than the size of this array, value will be truncated when read.

Outputs

Parameter Type Description
Done BOOL This output is TRUE during one cycle when the exchange is finished, whatever 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 Actual size of the CIP attribute answered by the server. If this size if greater than the size of the DATA input array, it indicates that the value was truncated.
Err UINT Main error report. Can be one of the following 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 in case of a UCMM error, this is the CIP general status error code.
EmErrExt UINT in case of a UCMM error, this is the CIP extended status error code.

Remarks

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 then you will get 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.

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;

Related Function Blocks