Read EtherCAT CoE SDO via Datalayer (Golang)

Hi,

I'm trying to read a CoE object from SAFEX-C.15 via Golang application. When using the Datalayer UI directly I can read successfuly:

The schema used for the flatbuffers is as per below:

include "addresstype.fbs";

namespace schema;

enum SDOFlags: uint32 (bit_flags)

{

noFlags = 0,

completeAccess = 1,

}

table SDORequest

{

addressType: Addresstype;

address: uint16;

objectIndex: uint16;

subIndex: uint8;

flags: SDOFlags;

data: [uint8];

maxLength: uint32;

}

table SDOResponse

{

data: [uint8];

}

table SDO

{

request: SDORequest;

response: SDOResponse;

}

root_type SDO;

The Golang code that implements the CoE request is as follows:

func (c *CallDatalayerClient) RequestCoE(node string) (w string){

var atype schema.Addresstype = schema.Addresstypefixedphysical

var sFlag schema.SDOFlags = schema.SDOFlagsnoFlags

builder := flatbuffers.NewBuilder(1)

schema.SDORequestStartDataVector(builder, 2)

for i := 1; i >= 0; i-- {

builder.PrependUint8(0)

}

dataRequest := builder.EndVector(0)

schema.SDOResponseStartDataVector(builder, 2)

for i := 1; i >= 0; i-- {

builder.PrependUint8(0)

}

dataResponse := builder.EndVector(0)

schema.SDORequestStart(builder)

schema.SDORequestAddAddressType(builder, atype)

schema.SDORequestAddAddress(builder, 1001)

schema.SDORequestAddObjectIndex(builder, 4104)

schema.SDORequestAddSubIndex(builder, 0)

schema.SDORequestAddFlags(builder, sFlag)

schema.SDORequestAddData(builder, dataRequest)

schema.SDORequestAddMaxLength(builder, 1024)

request := schema.SDORequestEnd(builder)

builder.Finish(request)

schema.SDOResponseStart(builder)

schema.SDOResponseAddData(builder, dataResponse)

response := schema.SDOResponseEnd(builder)

builder.Finish(response)

schema.SDOStart(builder)

schema.SDOAddRequest(builder, request)

schema.SDOAddResponse(builder, response)

requestObject := schema.SDOEnd(builder)

builder.Finish(requestObject)

v := datalayer.NewVariant()

v.SetFlatbuffers(builder.FinishedBytes())

//defer datalayer.DeleteVariant(v)

res := c.client.ReadSyncArgs(node, v)

fmt.Println("CoE request: %s", res)

if res != datalayer.ResultOk {

w = "Error!"

return

}

w = fmt.Sprintf("CoE request OK: %s", res)

return

}

The node is "fieldbuses/ethercat/master/instances/ethercatmaster/device_access/coe/sdo"

After the ReadSyncArgs function call the result reports DL_TYPE_MISMATCH.

Can you please help in understanding what is the problem? I believe the flatbuffer implementation is correct and there is no reason for the type mismatch error.

Thanks in advance.