Basic RSLogix help for a PLC newbie

Just learning about PLCs and self-teaching myself RSLogix 500 with a little MicroLogix 1400 controller. I have a basic understanding of the software but like to do things in the most efficient way.

I'm trying to create a basic program that will allow me to make the outputs turn on and off one by one automatically. Each output would, for example, have an LED attached to it.

So as a flow chart it would look like:

Output 0 turns on
Waits 3 seconds
Output 0 turns off
Output 1 turns on
Waits 3 seconds
Output 1 turns off
Output 2 turns on... etc..

I have an idea on how to do this but it doesn't seem very efficient and involves creating a separate TON for each wait. Is there a way I can re-use a TON or something?

What is the most efficient way of making a simple sequence of events like this?

Thanks in advance!

welcome to the site

Wow thanks! This is excellent! Didn't think of using the LIM to do this.

Thank you!

you can use the same timer in series along with step conditions being also made.

--]TIMER.DN[----]STEP=0[-----------------------------------------( L OUT1)--------
| |
---(mov 1 -> STEP)--



--]TIMER.DN[-----] / STEP=0 [-----]STEP=1[------] / STEP=2[---------( L OUT2)-----
| |
-----( U OUT1)-------
| |
---(mov 2 -> STEP)--

hopefully that was clear enough to follow

I have a basic understanding of the software but like to do things in the most efficient way.

Click to expand...

Another efficient way is to use a SQO sequncer instruction. Here is a 4-rung program that does your routine for 6 lights. You may adjust the S:4/8 bit (from S:4/0 to S:4/15) to get different ON time periods as desired.

Barneel said:

I have a basic understanding of the software but like to do things in the most efficient way.

Click to expand...

If you use Lancie1's suggestion and explore the SQO instruction, you can achieve most efficient by putting the SQO in a STI program file.

The sequence you are describing can be done with 2 instructions, not 2 rungs, just 2 instructions in the PLC !! It is very similar to the age-old "traffic lights" control that nearly all students are asked to program.

No disrespect to Lancie1, by the way, as you did ask for efficiency, his post is perfectly valid in the context.

But be careful when trying to make things most efficient, and especially if you are writing the code for other people to understand/debug/modify.

Most maintenance techs can cope with a few rungs containing XICs, XIOs, and some timers. They may not have the capacity, or the time, to learn and understand the workings of the SQO instruction.

Lancie1 said:

Another efficient way is to use a SQO sequncer instruction. Here is a 4-rung program that does your routine for 6 lights. You may adjust the S:4/8 bit (from S:4/0 to S:4/15) to get different ON time periods as desired.

Click to expand...

thank Lancie1, this is the best way to do it