runtime

panel1 · Nov 24, 2004

I need a better way to capture elapsed runtime on a motor? Im using a Micrologix 1200 with real time clock onboard. How can the RTC be used in this function. Thanks for your help. Im new to PLC's and this forum.

PS... how can I count past 32767 on my counter?
attached file is RSlogix 500

Martin T. · Nov 24, 2004

panel1,

Try to do a search on hour meters. If you don't find something I have a program with 11.41 years worth.

rsdoran · Nov 24, 2004

One way is to use multiple counters, 1 for each digit...ie counter 1 counts up to 10 then resets and puts 1 count in counter 2, counter 2 counts to 100 puts a 1 in counter 3 then resets. The numbers can then be manipulated to show whatever is needed.

I just realized you mentioned ML1200, the newer ones support 32 bit signed numbers which gives you 2,147,483,647. See if yours wont work with Long Integers.

Doug_Adam · Nov 24, 2004

Best way to capture run time depends on a few factors:

- End Usage
- Required accuracy
- Normal mode of operation and duty cycle.

A few methods I've seen or used are:

1, have a minute tick timer, each minute the motor is checked and if it is running, the counter is incremented. This is best for plants where the motor runs for extended time periods.
This could also be changed to single second increments. One note of caution, you should try to use a real time source for the tick, since the PLC timers aren't always accurate for this type of application.

2, Log start/Stop event to a SCADA PC. Then write a program to extract and summarise this information. I find this one works well if you also use Citect, since it is fairly easy to extract the information this way. The main problem you can have is PC crashing, but this can be reduced by creating a log buffer in your PLC.

panel1 · Nov 24, 2004

Martin T. said:
panel1,

Try to do a search on hour meters. If you don't find something I have a program with 11.41 years worth.

I didn't have much luck with hour meters search. I would appreciate a copy of your program. Thanks

panel1 · Nov 24, 2004

rsdoran said:
One way is to use multiple counters, 1 for each digit...ie counter 1 counts up to 10 then resets and puts 1 count in counter 2, counter 2 counts to 100 puts a 1 in counter 3 then resets. The numbers can then be manipulated to show whatever is needed.

I just realized you mentioned ML1200, the newer ones support 32 bit signed numbers which gives you 2,147,483,647. See if yours wont work with Long Integers.

Do you have an example on how to use Long Integers.. Im not clear.

Martin T. · Nov 24, 2004

Here is what I'm using. It running on a SLC5/04. Had to change the CPT to MUL's and ADD's. IF I messed this up someone will correct me.

Had to write this out, I couldn't transfer it from my laptop to my desk top, CD drive is giving me fits, need to replace the dang thing.

Ron Beaufort · Nov 26, 2004

a specific answer to a specific question ...

how can I count past 32767 on my counter?

this is one handy way ... basic idea: don't use the built-in CTU ... just make your own counter ...

[attachment]

Martin T. · Nov 26, 2004

So I guessing with Rons counter you should be able to drop some rungs off the hour meter I posted and you this.

Martin T. · Nov 26, 2004

Thanks Ron for the roll your own counter, never thought about using it that way. Learn something new all the time here.

panel1 · Nov 26, 2004

Thanks for the help

Thanks Ron and Martin for your help. I like the idea of not being limted to only 32767 .....however i have one more question concerning the F8 file. Will I be able to read this value same as an integer N7 file when using a Panelview interface. Thanks again for your help.

Martin T. · Nov 26, 2004

panel1 said:
Will I be able to read this value same as an integer N7 file when using a Panelview interface.

Yes.

When you set your numeric data display, and edit your tag just pick IEEE Float/ Real from the data type drop down.

panel1 · Nov 26, 2004

Martin T. said:
Yes.

{When you set your numeric data display, and edit your tag just pick IEEE Float/ Real from the data type drop down.

Click to expand...

Thanks... so much. This makes life much easier.

(.)(.) · Nov 27, 2004

I like the idea of not being limted to only 32767

Assuming that you would display runtime in 1/10 hours, do you anticipate 37 years of continuous operation? I'm not following where the problem is with using a standard counter for the runtime. Don't read this as a challenge to the thought...I feel like I may be missing something.

Martin T. · Nov 27, 2004

(.)(.) said:
Assuming that you would display runtime in 1/10 hours, do you anticipate 37 years of continuous operation? I'm not following where the problem is with using a standard counter for the runtime. Don't read this as a challenge to the thought...I feel like I may be missing something.

Why not 37 years!! Acutal with a float it would be 114years if my math is right.
I don't expect a compressor to run that long but why program something that your going to have to change later on down the road
because it ran longer then expected.

I've got runtimes at 5 years plus, 32767 only last 3.74years.

Most hour meters run at 1/10 of an hour as well as most car show 1/10 of a mile. It's just giving you something your use to looking at.

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