Timer in hour
- Thread starter fons04
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TConnolly
Lifetime Supporting Member
I'm not as fluent in CX as other PLCs, but I do have CX Programmer and have done a few Omron systems. Standard timers do not have hour time bases available and I'm pretty sure that there is not an hour timer FB available. You can use a standard timer and calculate hours however.
What exactly is it you are trying to do? Some of the Omron Guru's may be more helpful, but knowing what you are trying to do will be helpful in getting a solution for you.
What exactly is it you are trying to do? Some of the Omron Guru's may be more helpful, but knowing what you are trying to do will be helpful in getting a solution for you.
BITS N BYTES
Lifetime Supporting Member
Here is one way to do it on a CJ1 processor!
W1.0 turns on for one scan every hour.
You can use this bit as an input to a counter or just increment a word to your desired time value using [++ instruction].
W1.0 turns on for one scan every hour.
You can use this bit as an input to a counter or just increment a word to your desired time value using [++ instruction].
Last edited:
BITS N BYTES
Lifetime Supporting Member
I am not familiar with the CQM1 processor.
It must have an internal PLC Date Clock for the program to work. From memory I believe the PLC memory cassette contains the clock function.
The program works as follows:-
Auxiliary word A352 is the DAY|HOUR value of the PLC clock in a CJ1 processor [AR17 in a CQM1]. This changes value ONCE per hour.
The second rung stores the last DAY|HOUR value in a word of memory [In this case W0].
When the DAY|HOUR of the PLC clock changes the first rung becomes true and triggers W1.0 for one scan.
It must have an internal PLC Date Clock for the program to work. From memory I believe the PLC memory cassette contains the clock function.
The program works as follows:-
Auxiliary word A352 is the DAY|HOUR value of the PLC clock in a CJ1 processor [AR17 in a CQM1]. This changes value ONCE per hour.
The second rung stores the last DAY|HOUR value in a word of memory [In this case W0].
When the DAY|HOUR of the PLC clock changes the first rung becomes true and triggers W1.0 for one scan.
Tom Jenkins
Lifetime Supporting Member
This technique works in any processor, but of course the details of syntax and implementation vary.
Set up a timer for a one minute (60 second) pre-set with the required enabling logic. The output of the timer trips a counter, which then counts up every minute. Use the output of the timer to reset itself. This makes the timer zero out and begin timing another minute.
Set the counter pre-set to the number of minutes (hours x 60) requried. When the counter hits the preset time in minutes it will enable its output, and you are good to go.
Set up a timer for a one minute (60 second) pre-set with the required enabling logic. The output of the timer trips a counter, which then counts up every minute. Use the output of the timer to reset itself. This makes the timer zero out and begin timing another minute.
Set the counter pre-set to the number of minutes (hours x 60) requried. When the counter hits the preset time in minutes it will enable its output, and you are good to go.
Can you explain that by ladder logic?
Tom Jenkins
Lifetime Supporting Member
Here it is in Allen Bradly logic. The preset for this example is 20 minutes. For five hours you would obviously set the preset to 300 minutes.
Note that timer T4:5 sets on one scan, and resets itself on the next scan. I suppose that may induce an error of a few milliseconds each cycle, but if your desired time base is hours that shouldn't matter much. I've use the same basic technique on AutomationDirect.com, A-B, GE, Modicon, and Siemens.
Note that timer T4:5 sets on one scan, and resets itself on the next scan. I suppose that may induce an error of a few milliseconds each cycle, but if your desired time base is hours that shouldn't matter much. I've use the same basic technique on AutomationDirect.com, A-B, GE, Modicon, and Siemens.
BITS N BYTES
Lifetime Supporting Member
The explanation has already been provided to you.
If you don't understand it then you probably need to stop trying to program PLC's and move onto something simpler.
IS THIS THREAD A FLAME???
HHHMMMMM!!
TConnolly
Lifetime Supporting Member
Why not just fix the problem instead of programming a kludge around it? Thermocouples are about $35 bucks.
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