A matter of timers in RSLogix 5000

Hi mates!

I've got a very easy question here for you....

I need two clock pulse signals as the following scheme shows:


|----|----|----|

every vertical line means a clock each 2 minutes

---|----|----|---

for the second signal, I need the pulse goes true each minute,

I know how to generate the fist pulse with the DTR instruction and the system Clock ( GSV instruction) but I have some difficulties when setting ,as showed above, the pulse pattern for the second signal.

What I get is this, and that's not useful:

|----|----|----|
|----|----|----|

What I want, in the end, is to have two bits going true as I said first , for sampling an analogic input ( A level transmitter)so that I can compare the current read value with the one just inmediately before.

May someone help me please?

I would create a periodic task set to run every 60,000 milliseconds. In this task, toggle a bit.
In a continuous task, create a one-shot pulse when the clock bit goes positive and another one-shot pulse when the clock bit goes negative.

I would use 2 timers.

One resets/enables the other.

One timer is on time , the other is offtime.

The Timers can then be used to turn on an output that will be on and then off as the timers run and reset each other.

Once a minute increment a counter with a one shot. We don't care what the preset of the counter is or what the value the ACC ever becomes. Once a minute when the counter is incremented bit Counter.ACC.0 will change state. Every two minutes bit Counter.ACC.1 will change state.

00000 -> 0 minutes
00001 -> 1 minute
00010 -> 2 minutes
00011 -> 3 minutes
00100 -> 4 minutes
00101 -> 5 minutes
00110 -> 6 minutes
00111 -> 7 minutes
etc.

Alaric said:

Once a minute increment a counter with a one shot. We don't care what the preset of the counter is or what the value the ACC ever becomes. Once a minute when the counter is incremented bit Counter.ACC.0 will change state. Every two minutes bit Counter.ACC.1 will change state.

00000 -> 0 minutes
00001 -> 1 minute
00010 -> 2 minutes
00011 -> 3 minutes
00100 -> 4 minutes
00101 -> 5 minutes
00110 -> 6 minutes
00111 -> 7 minutes
etc.

Click to expand...

I use this idea in my current project.

I have several timer / counters in a FB that make these counts available for other functions.

I have a 10sec , a 1 min, a 10min, a 1hour. They reset at some number higher than I need to count and less than 999.

I did this because I ran into issues using what I thought should work.

I was creating a pulse but then it would stay true for more than one scan and caused multiple measurements where I only wanted one.

Thanks guys for all your tips. In the end, I haven't been able to sample my analogic input by following this programming way based on timers...

I have pusblished another thread more specificlly about it. http://www.plctalk.net/qanda/showthread.php?p=314179#post314179

Maybe having a look at it, you can understand what I exactly wanted to do.