who can show me how to use the DTR instruction

[plcnewbie]

If anyone can give me an example of using this instruction I would be happy. I have tried and failed. Lets say I want to track a preset value on a timer. If it is changed the DTR rung should go true. How do I do this?

 

[Gerry]

Note that the instruction is true for only one scan, since it also updates its reference when it detects a change. For checking an entire word, your mask should be -1.

 

[plcnewbie]

ok people I still seem to not be able to get this to work.


Line 1 - TON with a preset of whatever

Line 2 - DTR 1st space TON.pre, 2nd space -1 also tried 16#0fff, 3rd place TON2.PRE

Line 3 - TON2

Should this after making a change to the first TON cause the 2nd one to update as the reference I am trying to make it be?
Note: This is not how I plan on using it just how I dewcided to test out if I could understand how it works. Seems like I dont understand at all.

Thanks again people.

 

[Gerry]

ok people I still seem to not be able to get this to work.


Line 1 - TON with a preset of whatever

Line 2 - DTR 1st space TON.pre, 2nd space -1 also tried 16#0fff, 3rd place TON2.PRE

Line 3 - TON2

Should this after making a change to the first TON cause the 2nd one to update as the reference I am trying to make it be?
Note: This is not how I plan on using it just how I dewcided to test out if I could understand how it works. Seems like I dont understand at all.

Thanks again people.

OK
I tried what you described on a ControlLogix L1 processor and it works as you expected.
What platform are you using and what results do you get?

 

[Ron Beaufort]

see if this helps ...

in this simple example, you'll need to turn the "change_alarm" signal off manually ... a "toggle bit" action will do while you experiment ... set this up and make sure that the alarm is off ... then change the value of the timer's preset ... note that the alarm will come on ... now toggle the alarm off ... note that the alarm will stay off ... now change the value of the timer's preset again ...

this should take care of the DTR for you ... if not, post again and I'll take another shot at it ...

 

[OkiePC]

This PLC5 example sends a message to a GV3000 AC drive whenever the current limit needs to be changed. Any time N13:0 does not equal N13:100, the instruction wirtes the value of N13:0 into N13:100 and passes logic flow to the message instruction. To change the current limit in the drive, just change the value of N13:0.

I think what you want is to track changes to a timer preset. Use something like this to create a timestamped log. It uses file N99 (View file with four columns to see the hour, second, minute, and value each time it's changed) to log the 25 most recent changes with a wrap-around pointer:

 

[plcnewbie]

Looks good guys. Thanks alot for the replies so far. I have to try it out at work later. I am using a controllogix to do this on. I thought it should work also.

Thanks again I will update what my problem was later.