OEE line speed

[dumdum 1]

Hi

What would be the best way to track units per last 5 minutes?

[BobLfoot 301]

That's a very broad question with far too little information given.

Can you supply the following:

1. Anticipated Units Per Minute Maximum and Average

2. What AB PLC are you using {PLC5, SLC500, ControlLogix5000, CompactLogix5000, Micro800Series, MicroLogix}

[ElectronGuru 81]

While @BobLfoot is right, here's an over-generalized stab at it. I downloaded and tested on a 1756-5573, using V32. It works to count and record the parts over five-minute intervals.

 

 

Five Minute Part Counter.pdf

[dumdum 1]

Sorry i didn't provide the necessary information. 

Maximum units pr minute would be 8000 also average IF the machine is running.

Controller type: Compact logic and controllogix

Ideally i want real time update rate. But i'm aware that the amount of data would be too much. 

My thought was to load a counter value to an array of dint. (Dimension:5). Each dint of the array would represent count for each minute. Then use system clock to shift array every 1 minute. The average sum of the array would be units pr 5min updated every 1minute.

Is there a better way? 

 

[dumdum 1]

like this

 

Edited 29 Sep 2021 by dumdum

[Joe E. 259]

That may not quite work, but it's really close. The first COP instruction will copy the avg_array to avg_array_Temp, but offset by one position. If your arrays are 5 elements long, you're going to have a problem with it since you're starting the copy into the destination at register [1] for length 5. The last element that will get written to is element [5], but the last element of a 5-element array will be [4] (they start at [0]). That also leaves the value in avg_array_Temp[0] unchanged, which then gets copied back to avg_array[0]. During the times between pulses of System_One_Shot_Min, your avg_array will not have valid data. Element [0] will always be invalid except during the scan of that rung of code.

What I would do is use a COP instruction to shift the avg_array one position UP (closer to [0]) like this:
Source: avg_array[1]
Dest: avg_array[0]
Length: 4
That will move [1] into [0], then [2] into [1], then [3] into [2], and finally [4] into [3]. [4] will remain unchanged while the data in the other registers moves one position towards [0]. Then MOV your counter .ACC into avg_array[4]. The most recent minute's data will always be in element [4] of the array with the preceding 4 minutes' of data always there and available for display or other purposes. Then you can use the AVE instruction on the array to get the average of the last 5 minutes. You won't need the _Temp array or the MUL instruction.

You can also investigate the FIFO instructions (FFL/FFU), but they may be overkill for this.

The RES instruction of the counter may also cause you to be off by one count. If Unit_sensor is still on for the next scan after RES, your CTU will increment again, double-counting that part. To avoid that, you can either use an ONS instruction between Unit_sensor and CTU or MOV 0 into counter_avg.ACC instead of RES.