A、監(jiān)控單元COM_CTRL板后的RS232通訊線未接好 B、監(jiān)控單元COM_CTRL板壞 C、監(jiān)控單元通訊地址設(shè)置與后臺(tái)不一致 D、監(jiān)控單元COM_CTRL板沒(méi)有正確拔碼