6ES7643-7DB21-492135
PLC檢查是否有與編程器和計算機的通信請求，若有則進行相應(yīng)處理，如接收由編程器送來的程序、命令和各種數(shù)據(jù)，并把要顯示的狀態(tài)、數(shù)據(jù)、出錯信息等發(fā)送給編程器進行顯示。如果有與計算機等的通信請求，也在這段時間完成數(shù)據(jù)的接受和發(fā)送任務(wù)。
下面以FX系列PLC為例，來說明根據(jù)LED指示燈狀況以診斷PLC故障原因的方法。
在輸入處理階段，CPU將SBl，SB2和FR的常開觸點的狀態(tài)讀入相應(yīng)的輸入映像寄存器，外部觸點接通時存入寄存器的是二進制數(shù)l，反之存入0。
比較下二個程序的異同：
對于新行業(yè)而言，譬如風(fēng)電、太陽能等新能源領(lǐng)域，發(fā)展迅速，但對全局而言，仍然是星星點點，沒有辦法成為影響全局的助推力。新市場，還未形成。
不管輸出單元的LED燈亮還是滅，如果負載不能進行ON或OFF時，主要是由于過載、負載短路或容量性負載的沖擊電流等，引起繼電器輸出接點粘合，或接點接觸面不好導(dǎo)致接觸不良
用戶程序存儲器用于存放用戶載入的PLC應(yīng)用程序，載入初期的用戶程序因需修改與調(diào)試，所以稱為用戶調(diào)試程序，存放在可以隨機讀寫操作的隨機存取存儲器RAM內(nèi)以方便用戶修改與調(diào)試。

6ES7643-7DB21-492135
PLC checks whether there is a communication request with the programmer and computer, and if so, it will handle it accordingly, such as receiving the program, command and various data sent by the programmer, and sending the status, data and error information to be displayed to the programmer for display. If there is a communication request with the computer, etc., the task of receiving and sending data is also completed during this period.
The following takes FX series PLC as an example to illustrate the method of diagnosing the cause of PLC fault according to the status of LED indicator.
In the input processing stage, the CPU reads the status of the normally open contacts of SBL, SB2 and fr into the corresponding input image register. When the external contact is connected, the binary number L is stored in the register, and vice versa.
Compare the similarities and differences between the following two procedures:
For new industries, such as wind power, solar energy and other new energy fields, are developing rapidly, but for the overall situation, they are still bits and pieces, and there is no way to become a driving force affecting the overall situation. New markets have not yet formed.
No matter whether the LED light of the output unit is on or off, if the load cannot be on or off, it is mainly due to overload, load short circuit or impulse current of capacitive load, which causes the bonding of the relay output contact, or poor contact caused by poor contact surface
The user program memory is used to store the PLC application program loaded by the user. The user program at the initial stage of loading needs to be modified and debugged, so it is called user debugging program, and is stored in the random access memory RAM that can be read and written randomly to facilitate user modification and debugging.