Parts per hour display

[martin1000]

What is the easiest way of programming a omron plc to calculate parts per hour .The value will be displayed on seven segment displays

 

[Bitmore]

Do you have ANY input signals? Weight, machine speed, photo eye???
We'll need more info to be of any help.

 

[martin1000]

Displaying parts per hour

Sorry maybe i should have given more information about the application.The machine is used to mitre cut rubber extrusions.I will be able to count the the last step of each cycle.The problem is converting this to parts per hour

 

[electrified3]

I am not very familliar with Omron, but in AB or Modicon you are able to define a TOD, "Time of Day Clock", if you use this in conjunction with parts produced over time elapsed you can configure your statistical data, based on current elapsed time, past hrs, shift totals, etc. Just a little bit of math then. I have done this type of calculation before, just look into the Time of Day Clock function and use this as your time line for your calculations.

 

[kamenges]

The time it takes to make one part (in hours) is hours/part. The reciprocol of hours/ part ( 1/(hours/part) ) is parts/hour.
I am not a big Omron guy (although we do have one coming up on a project. Help, Jay!!!) but I suspect you can get at the accumulated value of a timer. Start the timer at the end of a cylce. Then at the end of the next cycle save the accumulated value before you reset the timer. This time will be the time to make one part in seconds (or tenths, hundredths or thousandths of a second) along with any transport and setup time for the material. Convert this time to hours, divide one by this number and you have parts per hour.

Keith

 

[electrified3]

As a note, are you going to design the circutry of the seven seg displays??? That data sucks, not alot of info there, Pviews, RSView, or marquee boards provide a much better solution for this type of data and for price may be comparible when considering I/O, 7 seg display costs, etc. The other formats give you much more flexibility with the same data, ie total production, up time down time, scrap, statistical time per part and allow a description of the data displayed to make it more useable, in addition to your origional data display question.
Take a look at ALPHA Automation and their displays and PC comm adaptors, a much larger display visible by alot of people with that type of data seams to have a big effect if looking to increase production, esspecially when manual operator labor is a factor.

 

[electrified3]

Sounds like you will do a whole lot of math and timers that may even be already be done for you in your plc, Up to you, if it has TOD will save you a pile of logic and timers

 

[Bitmore]

Ok Martin,
Now we got some meat to chew on, I don't know the model number of the PLC but some simple programming will do the trick.
some thoughts......
A sample timer used to time the sample rate of the counter. If you can detect the cycle end then you can count them. Set up a sample rate timer, a good place to start thinking about is this sample rate. It doesn't have to be a 1 hour timer. If your machine cycle time is around 5 to 10 seconds a 1 minute sample time would probably work for starters, you can optimize the sample rate once the darn thing shows signs of being "alive". The program will have an integer register set up for the displayed value, the register is updated with the new count at the end of every sample time. Some integer math will be needed to multiply the counter value to adjust for the "total" displayed. If you time the counter enable for 1 minute then at the end of that minute (timer done) multiply the counter value by 60 and put the answer into the display register. Reset the counter and timer and start the whole thing over again. You may have to do some data conversion to get your display to work, is your display a "package" or are you planning to build a display out of seven segment leds? If so, you can build a simple scanner to drive several led digits with a few outputs (save money). If so depending on what you have you may find that a Decimal to BCD command or something simular will be needed to get the data into the proper format for your display. Thats some things to chew on for awhile and depending on your PLC Model and what type of display interface you will use, is going to dictate what is needed in your display output programming, but I hope this has gotten the brain working full strength and ideas are beginning to take shape.

Bitmore

 

[Bitmore]

This is a personal record for me, 6 replies while I'm typing mine!
Keith has a viable solution as well, especially if the machine cycle varies allot over time, if the machine cycle is fairly constant or really constant the the sample rate method would work well.

Bitmore

 

[electrified3]

Bitmore, Sounds like a simple solution, just from my experiences that type of data, unless logged does not seam to prove a "true" relation to overall machine effectiveness. From my experiences you need to calculate effectiveness based on "entire shift" calclations. But it does depend on the extent of automation vs human factors. Past experience has shown me that anybody can make the #'s when someone is looking but when not looking then it falls. I guess it all depends on the nature of the operation.
But on the other hand if it is a highly automated machine in which you are trying to improve process using this data, a fast update over short periods is essential in order to determine the effectiveness of your improvement or lack there of, hehe.
I guess my suggestion was more based on my past experiences where there is alot of human interaction with the process and trying to sort out the true nature of machine effectiveness issues.

Bill

 

[electrified3]

Hey Bitmore, who you with, Been to several places in "Automation Alley" IE Auburn Hills

 

[Bitmore]

I am mostly independant/contractor, lately I've been working with Aarell in Troy, Mi. I live in Royal Oak, on 11 mile, "party central".
I thought the initial question asked was...

What is the easiest way of programming a omron plc to calculate parts per hour

Martin didn't say that the data was used for anything except a display. Well, that gave me the idea that the accuracy wasn't to important. One lost count here or there really won't stop production. I mean if you need dead nuts on data then perhaps some external device would be a better solution, like an external counter and a photo eye, then you could poll the device through some comms port and get the data that way. Well face it, his first post had absolutly no information about the application, so I figgured all he wanted was a relative speedometer for his machine. It may be just that, one way to optimize the logic timing would be to actually run at a certain machine speed for one hour and then count the parts and make adjustments to the timing or the math. I guess I was trying to do what he asked, make it easy, no, make it easiest! I still hope it helps get the brain juices flowing and perhaps when he replies we will all find out more about just what he is using this for..

Bitmore

 

[BobB]

I do not know which PLC you are using but most Omron PLCs have a time clock built in. You would only have to compare with the AR channels where the time clock information is held.

The other method would be to program a counter from one of the internal clock pulses and use that.

Both methods are very easy.

Many Omron PLCs also have a 7SEG function that can be used to drive outputs to a 7 segment display. Makes life very simple.

The CJ1 and CS1 also have a number of functions available that can be used to manipulate the time clock.

 

[electrified3]

Thats kewl Bitmore, my brother lives in Royal Oak also, so I know what ya mean by party central, he lives just off of 14 mile.

 

[Bitmore]

Thanks Bob, I wasn't certain if their was a 7 segment function like that available on that model. That would make things easier for the display portion of Martins question, and perhaps that was just what he was looking for.

PS Martin hows the project going?