Using VBA macro to call an ABAP code

Please try using below script −

Dim sapConn As Object
\Declaring a connection object
Set sapConn = CreateObject("SAP.Functions")

\Creating an ActiveX object
sapConn.Connection.user = "username"
sapConn.Connection.Password = "xxxx"
sapConn.Connection.client = "client#"
sapConn.Connection.ApplicationServer = "Application Server”
sapConn.Connection.Language = "PT"

If sapConn.Connection.Logon(0, True) <> True Then //Checking connection here
   MsgBox "Not able to login to SAP"
Else
   MsgBox "Login Successful !!"
End If
Dim rfcAcctDocCheck As Object
Dim oAcctHeader As Object
Dim otAcctAR, otAcctGL, otAcctAP, otAcctAMT, otReturn As Object

Set rfcAcctDocCheck = sapConn.Add("BAPI_ACC_DOCUMENT_CHECK")
Set oAcctHeader = rfcAcctDocCheck.Exports("DOCUMENTHEADER")
Set otAcctGL = rfcAcctDocCheck.Tables("ACCOUNTGL")
Set otAcctAR = rfcAcctDocCheck.Tables("ACCOUNTRECEIVABLE")
Set otAcctAP = rfcAcctDocCheck.Tables("ACCOUNTPAYABLE")
Set otAcctAMT = rfcAcctDocCheck.Tables("CURRENCYAMOUNT")
Set otReturn = rfcAcctDocCheck.Tables("RETURN")
               Dim qtLegs As Integer
Dim dt, comp, tpDoc, docRef, tpAcct, acct, customer, vendor, _
   curr, val, spLedger, ccenter, order As String
Dim curLine As Integer

For lin = 1 To UBound(reg)
   id = Format(tbPost.Cells(reg(lin).lin_ini, K_COL_ID), "0000000000")
   dt = getDate(tbPost.Cells(reg(lin).lin_ini, K_COL_DT))
   comp = getCompanyCode(tbPost.Cells(reg(lin).lin_ini, K_COL_EMPR))
   tpDoc = getDocumentType(tbPost.Cells(reg(lin).lin_ini, K_COL_TP_DOC))
   docRef = tbPost.Cells(reg(lin).lin_ini, K_COL_DOC_REF)
   otAcctGL.freeTable
   otAcctAR.freeTable
   otAcctAP.freeTable
   otAcctAMT.freeTable
oAcctHeader("USERNAME") = sapConn.Connection.user
oAcctHeader("HEADER_TXT") = "Excel"
oAcctHeader("COMP_CODE") = comp
oAcctHeader("DOC_DATE") = dt
oAcctHeader("PSTNG_DATE") = dt
oAcctHeader("DOC_TYPE") = tpDoc
oAcctHeader("REF_DOC_NO") = docRef
otAcctAMT.Rows.Add
otAcctAMT(otAcctAMT.Rows.Count, "ITEMNO_ACC") = Format(leg, "0000000000")
otAcctAMT(otAcctAMT.Rows.Count, "CURRENCY") = curr
otAcctAMT(otAcctAMT.Rows.Count, "AMT_BASE") = val
Next
If rfcAcctDocCheck.Call = False Then
   MsgBox rfcAcctDocCheck.Exception
End If