timing more than 999.9 seconds in DirectLogic

longzoo

Member
Join Date
Feb 2011
Location
pennsylvania
Posts
2
Hello, i have written a few programs in DirectLogic but never needed this type of timing. I am using a DL-06xx and I need an output to go true for approx 5 minutes then off for somewhere between 50 and 120 minutes. i wrote a small ladder with TMR1 counting to 9999 (999.9 seconds) and reseting itself after it is done (ie --TMRA1|>|999s----TMR1--). I then have a TMRA1|<|k3000 to Y0 output. this only gives me 16.6 minutes total time. so my output is on for 5 mins and off for 11.6 mins :(

i then attempted a second timer that reset the first so i now had 33.3 minutes. (i initially missed the fact that two sequential timers can't be used or their accumulators stomp on each other...so i am now using TMR1 and TMR3 :oops: ..but i digress)

i read in the manual that the timer can go to 17777 but this still doesn't get me where i need to be for time...

Is there a more graceful way to get longer time from a timer? i noted that constants will only allow you to enter 4 digits so i cant use a comparison for, say 36000 to get me an hour.

any nudges, or shoves ;), in the right direction would be GREATLY appreciated!
 
One thing in the past I have done is use a timer and have it reset after one minute. the timer will drive a counter for every minute.
 
A TMRA can go to 166666.6 minutes.

But to use its accumulated value, which is in two registers, you will have to use the double word compares (CMPD) not the inline compares.

E.g. for TMRA0 use LDD TA0, CMPD value
 
wow, quick responses! thanks guys, i didn't think of a timer/counter combo. i think that would be a bit easier than the CMPD option, but i will keep that in mind for any future projects.
Thanks!
 
Disclaimer - i don't use this PLC BUT!

increment an integer counter using 1 sec clock pulse on a oneshot rising?

Use > compare to track completion?
 
That is another approach but the small errors associated with any timer's timeout would be multiplied by the large number of seconds. This may be unacceptable.
 

Similar Topics

Hello, I am struggling to figure out some logic. I have an analog pressure sensor coming into the PLC and would like to have multiple timing...
Replies
4
Views
173
the plant I am supporting uses a siemens graph function to do some of the step procedures. in several steps it waits for the step to execute for...
Replies
1
Views
785
All Using a MicroLogix 1400. Not a huge program doing an auto stop function based on a calculated roll diameter Using encoder feedback for...
Replies
12
Views
3,276
Hi all, I'm trying to fully understand the different effects of the Loop Update Time parameter within the Logix PID instruction. I was always...
Replies
18
Views
4,662
Logix 1756-L82E processor. I am using the .ST bit to time how long a MSG takes to complete. This works fine except for every 10th MSG cycle takes...
Replies
5
Views
1,637
Back
Top Bottom