unit OPCDataCallback;

interface

uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,ComObj,OPCtypes,OPCDA, OPCutils,ActiveX;

type
  // 定義接收 IConnectionPointContainer 的數據返回類
  TOPCDataCallback = class(TInterfacedObject, IOPCDataCallback)
  public
    //異步通訊連接后，當連接項的數據發生變化時，服務器自動調用此函數
    function OnDataChange(dwTransid: DWORD; hGroup: OPCHANDLE;
      hrMasterquality: HResult; hrMastererror: HResult; dwCount: DWORD;
      phClientItems: POPCHANDLEARRAY; pvValues: POleVariantArray;
      pwQualities: PWordArray; pftTimeStamps: PFileTimeArray;
      pErrors: PResultList): HResult; stdcall;

    //異步通訊連接并執行異步讀操作后，當服務器接收到讀信息時，自動調用此函數返回數據
    function OnReadComplete(dwTransid: DWORD; hGroup: OPCHANDLE;
      hrMasterquality: HResult; hrMastererror: HResult; dwCount: DWORD;
      phClientItems: POPCHANDLEARRAY; pvValues: POleVariantArray;
      pwQualities: PWordArray; pftTimeStamps: PFileTimeArray;
      pErrors: PResultList): HResult; stdcall;

    //異步通訊連接并執行異步寫操作后，當服務器執行完數據寫如后，自動調用此函數返回寫操作的結果
    function OnWriteComplete(dwTransid: DWORD; hGroup: OPCHANDLE;
      hrMastererr: HResult; dwCount: DWORD; pClienthandles: POPCHANDLEARRAY;
      pErrors: PResultList): HResult; stdcall;
    //暫時沒有測試此功能
    function OnCancelComplete(dwTransid: DWORD; hGroup: OPCHANDLE):
      HResult; stdcall;
  end;

implementation
// TOPCDataCallback 方法

function TOPCDataCallback.OnDataChange(dwTransid: DWORD; hGroup: OPCHANDLE;
  hrMasterquality: HResult; hrMastererror: HResult; dwCount: DWORD;
  phClientItems: POPCHANDLEARRAY; pvValues: POleVariantArray;
  pwQualities: PWordArray; pftTimeStamps: PFileTimeArray;
  pErrors: PResultList): HResult;
var
  ClientItems: POPCHANDLEARRAY;
  Values: POleVariantArray;
  Qualities: PWORDARRAY;
  I: Integer;
  NewValue: string;
begin
  Result := S_OK;
  ClientItems := POPCHANDLEARRAY(phClientItems);
  Values := POleVariantArray(pvValues);
  Qualities := PWORDARRAY(pwQualities);
  for I := 0 to dwCount - 1 do
  begin
    if Qualities[I] = OPC_QUALITY_GOOD then
    begin
      NewValue := VarToStr(Values[I]);
      showmessage('新的返回數據從 item '+ inttostr(ClientItems[I])+'接收到，其值為: '+NewValue);
    end
    else begin
      showmessage('新的返回數據從 item '+ inttostr(ClientItems[I])+'接收到，但數據質量有問題');
    end;
  end;
end;

//此項中具體內容為本人添加，可實現異步讀函數的回調，功能考慮不完善（錯誤判斷等）
function TOPCDataCallback.OnReadComplete(dwTransid: DWORD; hGroup: OPCHANDLE;
  hrMasterquality: HResult; hrMastererror: HResult; dwCount: DWORD;
  phClientItems: POPCHANDLEARRAY; pvValues: POleVariantArray;
  pwQualities: PWordArray; pftTimeStamps: PFileTimeArray;
  pErrors: PResultList): HResult;
var
  Values: POleVariantArray;
  NewValue: string;                           //保存返回的數據
  Qualities: PWORDARRAY;
  I: Integer;
begin
  Result := S_OK;
  Values:= POleVariantArray(pvValues);        //異步讀返回數據
  Qualities:= PWORDARRAY(pwQualities);        //異步讀返回數據質量
  for i:=0 to dwCount - 1 do
    begin
      NewValue := VarToStr(Values[i]);
      if Qualities[i] = OPC_QUALITY_GOOD then
        begin
          ShowMessage('回調讀函數響應,其值為：'+NewValue);
      //    form1.ASyncreadEdit.Text:=NewValue;
        end
      else
        ShowMessage('回調讀函數響應,但沒有讀到正確數據');
    end;
end;

//此項中具體內容為本人添加，可實現異步寫函數的回調，功能考慮不完善（錯誤判斷等）
function TOPCDataCallback.OnWriteComplete(dwTransid: DWORD; hGroup: OPCHANDLE;
  hrMastererr: HResult; dwCount: DWORD; pClienthandles: POPCHANDLEARRAY;
  pErrors: PResultList): HResult;
var
  WErrors:PResultList;
begin
  WErrors:=PResultList(pErrors);
  if WErrors[0] = S_OK then
     ShowMessage('寫回調函數響應,異步寫完成')
  else
     ShowMessage('寫回調函數響應,但異步寫數據沒有正確寫入');
end;

//此函數暫時沒有測試
function TOPCDataCallback.OnCancelComplete(dwTransid: DWORD;
  hGroup: OPCHANDLE): HResult;
begin
  Result := S_OK;
end;

end.