Second, the OPC specification is introduced and the Historical Data Access and Data Access specifications in it are analyzed in detail.The operating of HDA is also discussed in this paper.是什么意思_Second, the OPC specification is introduced and the Historical Data Access and Data Access specifications in it are analyzed in detail.The operating of HDA is also discussed in this paper.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句