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MELSEC-A series is that it was serious even to expand the program size like the subprogram that receives a lot of limitations as it is a limitation of OS of "CPM", the maximum program capacity is a step by 30K, and the plural cannot be programmed, switches the bank, and uses it. Having been developed there quite new by using OS and architecture is QnA series. It is succeeded, it makes to compact, and what made efficient is latest model Q series.
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Commentor / R.Takeuchi |
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The ladder is not "One scroll" any longer |
Though we thought that a program was an image of one scroll, from the Q/QnA series can be divided into two or more programs called it "multiple program" method. Have you already been used by multiple program.
For example, though the special relay "M9038" that switched ON only 1 scan after RUN often mostly sets up like an initial value, it is an unnecessary circuit if processes it only once when you switched on the power supply.
But when this circuit is in main program, the output doesn't work on, and the conditional judgment such as "LD" and "AND" is actually processed and the scan time will be slow every time.
Tact time need not be on purpose slow because it is scan time = production capacity. If engineer, you will think that you make operation of speed up at 1sec or 1ms.
We always lose at the methods. When the similar logic is displayed, it is the methods that whether to do the loop processing or whether it is necessary to write in direct or, to divide the file by two or more times. Such a time, we select the methods that the most comprehensible and doesn't happen at the trouble.
For example, when the thermometer, the barcode reader and the barcode printer are communicated, I think that had better divide the file. It is possible to do debug by itself. In main program side, we only need in the PV value, the SV value or the barcode of thermometer or written the value of the barcode, I think that the program area needs not to be the same. Oppositely, I think that it is the difficulty to see because it is long does.
Then, how about conveyer A and conveyer B in case of "start turning the motor when it is detected the work throw sensor, and when goes throw out the work throw sensor, the motor is stopped".
Except for in case the number of conveyers is numerous, I think that it is directly entered in the main program.
As the control logic is not very complex, by using of "For-Next command", though it may think that the file is divided each conveyer ,the sensor often causes miss action of operation of mechanism to abnormally movement until the adjustment becomes perfect
At such time, if the ladder program is written by the loop processing, seeing the circuit, the contactor cannot be monitored. If the file is divided, it is necessary to switch all the way to screen. It causes the adjustment time to be made uselessly prolonged.
- Because you can see two or more files like this when "PC Read" is done, which wants to be read, you can be selected.
Though I wrote variously, too much dividing the file, it is non sense that the response was worse, and when other people are seen the program, cannot understand completely. "The machine is made to operate comfortably" is a main purpose. We have to keep in mind like writing a program that is more high speed, more comprehensible (It makes easy to debug it).
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Inside MELSEC
Advanced OPC