S7-200自由口通讯示例_百度文库http://wenku.baidu.com/link?url=DlmeTbJvVcMGEOouGiAXgswA85O2TlUhASl4b5v_oi2g_xaQGErVppbKdoH5IjzEM_QVOT1Z_FXo2FrekpTxSiEhY_izR4bC_IH2Br_5hKK
