Mitsubishi Q series/GX developer...target speed RPM

[Mas01]

Thanks for this parky. From what you describe, is no wonder that the operators don't use the target speed function if it's difficult to control.
For info X214 (cyclic control) goes TRUE when a physical key is moved to the ON position. None of the operators ever touch that key and leave it in the OFF position! The original operators have retired and the current ones were told about the target speed being difficult to control.
I will get more info etc on Monday.

 

[drbitboy]

Actually, I think it's just a little bit clever, if poorly implemented, something like the repeat function on a keyboard.

Maybe the original programmer chose poor timing parameters.

Or maybe it is unreliable because the timer is something like a Siemens timer, and the T19 timing logic (1888: [N.C. T19]---[T19 K1=100ms]) is almost immediately before the use of its pulse on the speed change rung (1960), so that timing logic clears most pulses before the speed increment/decrement logic, and the few that get through, because the timer expires in the brief period between 1888 and 1960, are random and irregular. Moving the timing logic to after the speed logic might fix it.

 

[parky]

That's what I believe, however, it is poorly implemented plus as Mas said there are buttons on the HMI to do the same job where are they ?.
Also, from experience because the coms update will vary, the HMI buttons would be very difficult to implement in many cases, I know from experience that buttons or touch elements on HMI's cannot be relied upon to mimic the operator press time, I have had problems a few times with this a quick press does not always send the change of state as by the time the OS of the HMI looks at it the button has been released, this is why some of the biggest faults on HMI's is damaged buttons or Touch elements as operators tend to get irate.
This tends to be dependent on the HMI make but have seen it quite a few times.

 

[drbitboy]

Here is why the Siemens style of timer is semi-broken*, IMNSHO. My issue boils down to indeterminacy: you cannot know when the timer will be detected as having expired (.Q = 1).



* I preface that with "semi-" because the problem can be fixed by coding an input map, so it's not a big deal in the end.

 

[Mas01]

The problem is that some of the code is not in your pics, for example M71, however, it does appear it is meant to work from what I can see if the speed is below the Max speed then it allows the speed to be increased & the same for speed reduction.

Also the program is very messy & contains more code than is needed.
Is the speed reference i.e. target speed fed back as actual speed
The bottom two rungs where the compares are done is purely to limit the output to the minimum & maximum speed.
It seems weird that the inhibit bit M71 is only in the increment how is this bit controlled.

See rung 2017 for M71...