/// <summary>
/// 从默认的OPC项读取值
/// </summary>
/// <param name="value">待读取的值</param>
/// <param name="message">返回的错误信息</param>
public bool ReadItemValue(out string value, out string message)
{
value = string.Empty;
try
{
if (DefaultGroupInfo == null)
{
message = "未找到默认组";
return(false);
}
if (!DefaultGroupInfo.ReadValues(out message))
{
return(false);
}
if (DefaultGroupInfo.ItemCount > 0)
{
value = DefaultGroupInfo.ListItemInfo.Last().Value;
}
GC.Collect();
}
catch (Exception ex)
{
message = string.Format("从服务端句柄为{0}、标签ID为{1}的标签读取值失败：{2}", ItemHandleServer, ItemId, ex.Message);
return(false);
}
return(true);
}
/// <summary>
/// 向默认的OPC项写入值
/// </summary>
/// <param name="value">待写入的值</param>
/// <param name="message">返回的错误信息</param>
public bool WriteItemValue(string value, out string message)
{
try
{
if (DefaultGroupInfo == null)
{
message = "未找到默认组";
return(false);
}
if (DefaultGroupInfo.ItemCount > 0)
{
DefaultGroupInfo.ListItemInfo.Last().Value = value;
}
if (!DefaultGroupInfo.WriteValues(out message))
{
return(false);
}
GC.Collect();
}
catch (Exception ex)
{
message = string.Format("向服务端句柄为{0}的标签写入值{1}失败：{2}", ItemHandleServer, value, ex.Message);
return(false);
}
return(true);
}
/// <summary>
/// 设置默认的OPC项，假如已添加，则移除后再重新添加（同一时刻默认标签只有一个）
/// </summary>
/// <param name="itemId">标签ID</param>
/// <param name="clientHandle">标签的客户端句柄</param>
/// <param name="message">返回的错误信息</param>
/// <returns></returns>
public bool SetItem(string itemId, int clientHandle, out string message)
{
try
{
if (DefaultGroupInfo == null)
{
message = "未找到默认组";
return(false);
}
//初始化OPC项信息并在默认OPC组中添加
List <OpcItemInfo> list = new List <OpcItemInfo>()
{
new OpcItemInfo(itemId, clientHandle)
};
DefaultGroupInfo.SetItems(list, out message);
if (DefaultGroupInfo.ItemCount > 0)
{
OpcItemInfo item = DefaultGroupInfo.ListItemInfo.Last();
//保存默认OPC项的客户端句柄，服务端句柄，标签名称
ItemHandleClient = item.ClientHandle;
ItemId = item.ItemId;
ItemHandleServer = item.ServerHandle;
}
}
catch (Exception ex)
{
ItemHandleClient = 0;
message = "移除或添加标签时发生错误:" + ex.Message;
return(false);
}
return(true);
}
