Equipment Runtime (Totalizer?)

Good morning, All...

I searched the forum yesterday and this morning and was surprised that I didn't find more on this topic. Essentially, I would like to track the amount of time that a piece of equipment runs for. Call it runtime, elapsed time - totalizer?

SLC 5/03 (1747-L553) Processor

It seems relatively simple:

-If Pump #1 is running
-Start Runtime Timer (Retentive)
-When Pump #1 stops running
-Stop Runtime Timer and Move Accumulated Value to register

I don't know for sure how long the pump(s) will be running and it will not necessarily be the same each time they run. That being said, I cannot depend on the "timer done" bit to move my accumulated value into memory.

Can anyone provide some insight on what a good approach might be?


Thank you,
Justin

use the RTC status bits s:40 hours s:41 minutes s:42 seconds and add them to a memory location. Yes this subject as been covered before just under different search headings

If I were to create a rung that said:

If Runtime Timer is timing (TT), MOV the accumulated time from the timer into a register. This, I believe would just move the accumulated value at that time into memory. Is there a way to utilize the accumulated value such that the HMI display would update in realtime?

The big question with these runtime counters always is...How large do you expect the value to become and how accurate do you need it to be?

As I said, unfortunately I do not know how long the pump(s) will run, so plan on worst case.

If possible, I would like to be accurate within one minute.

One thing that often gets overlooked when setting up a PLC-based run-time timer is that it will be reset whenever you download a program change. If you ever make program changes off-line then download them later, the timer will be reset to the value at the previous save.

If you want a true run-time meter, I'd recommend an "old-fashioned" hardware timer. They're cheap and easy to install. They just don't end up on an HMI, but the can certainly be available at the control panel.

OZEE said:

One thing that often gets overlooked when setting up a PLC-based run-time timer is that it will be reset whenever you download a program change. If you ever make program changes off-line then download them later, the timer will be reset to the value at the previous save.

If you want a true run-time meter, I'd recommend an "old-fashioned" hardware timer. They're cheap and easy to install. They just don't end up on an HMI, but the can certainly be available at the control panel.

Click to expand...

I second OZEE's statements. Way too easy to loose the information over a download. You can try to always remember to upload before making changes but ... we're all human.

OZEE and ndzied1,

I appreciate the recommendations. Your point is well taken, however the client has asked for a software-based runtime counter. It is too late in the game to make any changes now.

What I typically do for Runtime meters is use a retentive timer (RTO) set to 3600 seconds (1 hour). When that timer is done, I reset it and increment an integer (N7:xx) that shows the hours used. The hours are then shown on the panelview, etc. I add a couple checks to make sure that the hours register rolls-over (set it to zero if it is greater than 32000). It wouldn't be too hard to add a minutes elapsed to this scheme as well if you needed it, but hours has always been the standard on the equipment that I deal with.

I dont know the plc software your using but you should have a system bit that pulses every minute.
Just write a simple section that with the run feedback on and the system bit pulsing(rising edge of the bit) increment a double word. You might loose a couple of seconds here and there at startup but this should be more than accurate enough for a pumps running hours.

Count hours in .01 hour increments (36 seconds) or .1 hour increments (360 seconds) using a float.





Notice that the timer is RTO and that it is never reset - this keeps the porogram scan time from being added into the total and retention keeps track of the time between each .01 increment even if the motor is stopped.

http://www.plctalk.net/qanda/showthread.php?t=26446

http://www.plctalk.net/qanda/showthread.php?t=35043


A thread on things to be aware of:
http://www.plctalk.net/qanda/showthread.php?t=31068


If you are using a ControlLogix:
http://www.plctalk.net/qanda/showpost.php?p=251927&postcount=5

Hi all,

Heres a runtime shift counter I made up a few years ago. Still working on a few machines we have. Its timing off an output that does the count and moves it into an indirect address. And after the shift is over the pointer moves it by 10. Its only good for 7 days,
and only works on a/b 5.05 as you need s53 bit for day of week.