繼續學習。

6.4 Power fail signal (PF) and power fail 電源故障訊號和電源故障 I/O modules maintain the last values until they have recognized the connectioninterruption and then adopt safety values until the CPU module sends actual valuesafter restart. In case of power failure of the I/O module, output levels adopt zerovoltage and/or zero current. I/O模板識別出最後一次值直到它們識別出連線中斷，然後採取安全值，直到CPU傳送實際值後重新啟動。當IO模組斷電時，輸出零電壓和/或零電流。 After voltage returns, I/O modules only change their output level when the CPUmodule communicates actual values. 恢復電壓後，當CPU模板通訊實際值時，I/O模板改變其輸出值。 6.4.1Power fail signal (PF) and no power fail 電源故障訊號（PF)和斷電故障

PF < 15 ms 電源故障時間 < 15ms

While the power fail signal is active, the CPU module or the AC 800F controller does not communicate current values; I/O modules independently maintain the last values. 當電源故障訊號啟用，CPU模組或者AC 800F控制器無法通訊當前值；I/O模組 獨立的保持前一次的數值。

PF > 15 ms 電源故障時間 > 15ms

I/O modules maintain the last values until they have recognized the connection interruption to the CPU module or to the AC 800F controller before they adopt the configured safety values The safety value are maintained until the AC 800F controller has performed a warm start and provides the I/O modules with new values. 在採取設定的安全值之前，I/O模板保持最近的數值直到識別出與CPU模板或者 AC 800F控制器的連線中斷。保持安全值直到AC 800F執行熱啟動，提供I/O 模板新的數值。

6.4.2Power fail signal (PF) and power fail 電源故障訊號和電源故障 I/O modules maintain the last values until they have recognized the connectioninterruption and then adopt safety values until the CPU module or the AC 800FController provides them with the current values upon restart. In case of power failure ofthe I/O module, output levels adopt zero voltage and/or zero current. I/O模板保持最近的值直到識別出連線中斷。然後採取安全值直到CPU模板或者AC 800F控制器重新啟動，提供給它們最新的數值。當I/O模組斷電時，輸出零電流或者零電壓。 When power is supplied again, the I/O modules change their output level only whenthe CPU module or the AC 800F controller communicates current values. This doesnot apply to the analog output modules. As long as there is no failure in the externalpower supply, they keep the last values. Only when the power supply of the AC 800Fcontroller is ensured again, the outputs are de-energized. 當電源恢復，只有當CPU模組或者AC 800F模組通訊當前值時，I/O模組才會改變其輸出數值。這不適用於模擬量輸出模組，它們保持最近的數值。只有再次確認AC 800F控制器的電源供應時，輸出斷電。 6.4.3Safety values for field devices 現場裝置安全值 The cyclic data exchange between the PROFIBUS master and the connected slavesis monitored. When the cyclic data exchange is interrupted, the safety values can be assumed. The output channels feature manufacturer-specific safety values.Depending on the process requirements, the safety values for input channels can beconfigured to "Hold the last value" or to a particular value/status. PROFIBUS主站和連線的從站之間的週期性資料交換被監控。當週期性資料交換中斷，採取安全值。輸出通道採取製造商分配的安全值。根據工藝需求，輸入通道的安全值可以配置為“保持最後一次值”或者特定的值/狀態。

A possible power failure can be evaluated by means of a system variable and used in the user program. 可能的電源故障可以通過系統變數來評估，使用在使用者程式中。