Timers

hey peeps i got a ? for u all
I am working on cleaning up a old program, and have run across some logic that i don't understand. the logic is for a flasher.
but i have never seen it done before and was wondering if some one could explain it to me. here is the logic.
sorry guys this is in a plc5

The first rung basically resets the timer off its own done bit everytime its finished counting to 500 so it runs "forever".

The remaining rungs monitor individual bits in the timer's accumulating value and drives the internal coils in B3. Bit 5 will flash 4 times faster than bit 7.

Hope that helps.

PS: I believe the rate on b3/0 will be 0.64 secs and the rate on b3/1 will be 2.56 secs, both 50% duty (except when the timer resets).

Sure...

Basically, your timer is set for 5 seconds, but will accumulate a number in hundredth of seconds (decimal). When bit 5 or bit 7 (binary) of the ACC word is the corresponding rung will be activated... For example: if you used bit 0 instead of bit 5 you you would flash every other 100th of a second... Not sure if that simplifies it for you...

Flasher

Instruction bit: 13 = DN (done) bit when the ACCUM (accumulated) time equals the PRESET time.



Accumulated Value (ACC)

The number of time base intervals the instruction has counted.



Preset Value (PRE)

This is the set point that you enter in the timer instruction. When the accumulated value becomes equal to or greater than the preset value, the done status bit is set. You can use this bit to control an output device.



This output instruction begins timing (one hundredth of a second intervals) when its rung goes "true." It waits the specified amount of time (as set in the PRESET), keeps track of the accumulated intervals, which have occurred (ACCUM), and sets the DN (done) bit when the ACCUM (accumulated) time equals the PRESET time.

As long as rung conditions remain true, the timer adjusts its accumulated value (ACC) each evaluation until it reaches the preset value (PRE). The accumulated value is reset when rung conditions go false, regardless of whether the timer has timed out.



The done bit resets the timer every time the preset equals the accumulation and continues “forever”. The bit 5 is the accumulating value of the timer and will flash B3/0 and bit 7 is another accumulating value of the timer and will flash B3/1 a little longer than B3/0. Never seen it done this way but beats using two timers.

yes it does
i knew how the timer works, it was the t4:0.acc/5 and t4:0.acc/7 bits that i didn't understand. i have never seen it done that way before but thanks agian for the help

looks like you've got it all figured out ... but there's a little bit (no pun) more information in this post from awhile back ...

thanks ron that helped a lot now i understand what is going on