Allen Bradley Plc2 Timer Functions??

Hello All,

I am working with an old PLC2 and we had some kind of power surge that screwed our program up. I have gone back with an old hardcopy and tried to recreate the program. The problem I am having is that some of the rungs that went missing contain the timers that are not functioning properly. I can view the preset value with thumbwheel and display panel, but I can't change it using the store button. Do I have an address for the preset value that is not defined? I can go in the program and enter a constant and the timer functions, but I can't change it using the thumbwheels??? There appears to be no difference in TONs that are working and the ones that aren't in the ladder.

Any help would be appreciated!

Cheers!

Scott

SCOTT-SUPERMAN said:

Hello All,

Click to expand...

SCOTT-SUPERMAN said:

I am working with an old PLC2 and we had some kind of power surge that screwed our program up. I have gone back with an old hardcopy and tried to recreate the program. The problem I am having is that some of the rungs that went missing contain the timers that are not functioning properly. I can view the preset value with thumbwheel and display panel, but I can't change it using the store button. Do I have an address for the preset value that is not defined? I can go in the program and enter a constant and the timer functions, but I can't change it using the thumbwheels??? There appears to be no difference in TONs that are working and the ones that aren't in the ladder.



Any help would be appreciated!



Cheers!



Scott

Click to expand...

Scott,

You are about to find out what the definition of SOL is. And it is not the abbreviation for Solenoid. But, back to the problem at hand, you have not given me much to work with here. You seem to be confused and I can certainly understand that. The PLC2s are very old and only some of us "experienced" guys even remember what they were. Since you are not giving many details here I will try and answer your questions as I semi-understand them.

1. Do I have an address for the preset value that is not defined? Answer: Probably not! The preset is necessary for the timer to accumulate time given that the rung is true so it can operate.

2. I can go in the program and enter a constant and the timer functions, but I can't change it using the thumbwheels??? Answer: This may not be a question as much as it is an observation. Of course you can change the preset while you are in the program, I presume you mean online with the processor running, but it is also possible to change the preset and then download the changes. But, the second part of this statement, if the thumbwheels were part of the installed equipment in the beginning, then part of the program you lost was there to read the thumbwheel settings and then get that value to the proper timer preset by some means. You will have to re-create that part to get them working again.



After you have gotten some work done, try and define your questions more clearly and the responses from here will doubtless be more focused as well. Good luck and keep coming back till you get this thing licked. We are here to help!

Hello Randylud,

Thanks for reply. I do know the addresses or "words" of both the accumulated value and the preset value. From what I have read on the Allen Bradley site, the preset "word" address is always 100 more than the accumulated value.

The thumbwheels were part of original machine. All of the rungs related to introducing the thumbwheel information to the program are there. I went through the program that I was able to extract from the PLC rung by rung and checked every rung.

I'll go back and verify the function of that portion of the logic.

Cheers!

Hello Again All,

A little more to the point, I hope this time.

I have a rung in which I have a normally open contact representing selecting vacuum delay, a normally open contact representing an input from a "store" pushbutton, and a GET from the thumbwheel. The first two contacts are true and the DATA from the thumbwheel reflects correctly while I am online. When these conditions are true I would like to PUT the Word into Address 300. I would like to then use the Word in Address 300 as my preset value on a TON with Address 200. In GE FANUC 90-30 programming, I would simply type the address of the register where the value is stored and be done. How do I do define my preset as a value stored in an address rather than simply typing in a constant?

Hope this is explicit enough.

Cheers!

Scott

SCOTT-SUPERMAN said:

Hello Again All,

A little more to the point, I hope this time.

I have a rung in which I have a normally open contact representing selecting vacuum delay, a normally open contact representing an input from a "store" pushbutton, and a GET from the thumbwheel. The first two contacts are true and the DATA from the thumbwheel reflects correctly while I am online. When these conditions are true I would like to PUT the Word into Address 300. I would like to then use the Word in Address 300 as my preset value on a TON with Address 200. In GE FANUC 90-30 programming, I would simply type the address of the register where the value is stored and be done. How do I do define my preset as a value stored in an address rather than simply typing in a constant?

Click to expand...

It's that simple. If you put the value from the thumbwheel into 300, you have set the preset of a TON at 200 to the thumbwheel value.

The timers in a PLC2 don't have the option of a constant for a preset. The preset is always whatever is in the word 100 more than the TON address (which holds the accumulator). Note that the preset and the accumulator are in 3 digit BCD. So only the first 12 bits of each word are used for the value. The DN, EN flags are in the high bits of the accumulator. I believe it's bit 15 = DN, bit 17 = EN.

Hope this helps.

Thanks MELLIS!

I went back and checked the logic and I had a typo where I had selected address 300 but it was assigned to a simple coil instead of a PUT. Edited lines and they work properly.

Sorry to bother you guys with a typo!

Thanks for looking and offers to help!

Cheers!