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The label programming is a function that the development can be advanced even if the number of a real device is not decided. The sight, because the circuit is expressible by a peculiar name such as not the sign of "X10" or "D999" but "C/V exit sensor" and "Number of production", the program that understands easily as anyone can see can be constructed.
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Commentor / R.Takeuchi |
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Ideal and reality of label programming |
What is the "label program"? It takes as an example of usual the conveyer control. Let's see an actual code.
Here is continuously arranged some conveyers. When the sensor of the entrance is kicked, the conveyer is running. When the next entrance sensor of conveyer is kicked, is stopping. This simply program is as following below .If it writes with a general ladder is as following below.
If this circuit is written by using "the label program", it becomes the following below.
Which is better? It might be non sense to compare this two, though it tends to compare. To begin with, there should have been essence of "the label program" as for "Even if the I/O address was not decided, the program development can be done".
However, to the best of my knowledge, it is general to go through the process of previously deciding the I/O address by the design phase and then developing software. It might be difficult assumed to install the circuit with not decided the I/O address and there might be that a case of developing the program before the mechanism operation is fixed by the I/O address different in each device and ,of a period of delivery is priority.
Moreover, there might have been visual demand that the program written with the label was maintenance easily than the program written by a usual I/O number. Though it installs with a "real device", and it debugs it while doing the comment display as shown in the figure below if it is me. Because it is avoid doing a complex thing that defines "the compile operation" and "the table convert" and simple thing doesn't generate the mistake, and seem to be the same as no peculiar mark of "CV3 entrance sensor" etc, even if it writes in the mark tube, when wire the line.
Change topic. It introduces other usage though it doesn't understand whether convenience or not. "The label program" and "the real device program" can be displayed at the same time by using the menu "Edit" and "Device display" like understanding a "real device" when "the label program" is debug on two step screen. In the case for which the wiring check is necessary, it is necessary to understand the I/O address immediately still.
Some notices: For user that the label program is used.
- The compile operation is needed without fail. Tentatively, writing online.
- The index cannot be modified to the label.
- When the label is used for the division instruction, the surplus is not stored. When it is necessary, an array type variable or a real device is used.
- When the number of elements to be stored the result by the multiplication instruction etc. is insufficient, a sequential area of a real device is overwrited.
- "Device with an automatic crack" area is taken. Default is as follows.
1) Word Device : D6144-D12287
2) Bit Device : M4096-M8191
3) Timer : T64-T2047
4) Counter : C512-C1023
This range can be changed by "Device setting with an automatic crack" of "Edit" menu with the label variable screen displayed.
- The label cannot be used for the ladder part of the SFC program.
- Writing, and the code of a real device after it compiles is written in CPU, and executed as for PC when operating it. The code after it is converted into a real device is read when Reading is operated, and former label code is not restored. It is necessary to keep former project data in PC.
- Though it came to be able to store former data in CPU together by using since version 8.03 of GPPW. It writes and no adjustment occurs to online program changes because only the execution code is corrected and former data doesn't change.
As mentioned above, there is only a restriction "It is necessary to make it to the label program to use the function block", and I use the label program only at that time though I hardly use the label program because there is a troublesome operation/specification.
Let's try other usage, as there might be a more convenient usage in the part that I do not know,
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Inside MELSEC
Advanced OPC