sequencer help.

[awmiller42]

hello,
im kind of new here, but here goes:

"If you are going to control a machine with 100 output actuators and you want to use sequencers to
control the 100 outputs, what is the minimal number of sequencers that will be needed?"

this is on my homework today and unfortunately my teacher isn't clear when he teaches and expects us to already know how to program can anyone help with this in any way or try to explain it a little more so that i know what i am doing?

 

[PLC Pie Guy]

Ill try this one.
Sequencers was one of the first things I learned in PLCs so here goes.

I am thinking you would want to know what platform you are using. If it is something 16 bit than you would want to use 7 sequencer output instructions to cover all the necessary outputs. Like wise if you were using a 32 bit platform you would need 4 sequencer output instructions. This is provided of course that you wanted to assign each bit to an output. Each example would give you spares after assigning the 100 outputs.

You can have as many positions in you SQO as you like so if you are going for 100 steps that is fine.

Hope this helps.

 

[awmiller42]

thanks for the help, we are using allen bradley rs logic 5000 16 bit (i think) so it would be 7, and i see how you got that to, thanks for the help!

 

[PLC Pie Guy]

If you are using RSLogix 5000 than it is a 32 bit platform.

16 bits to an integer
32 bits to a DINT

 

[RonJohn]

Welcome to the forum awmiller42. It'd be good if you could clarify your question some. From my perspective, your answer will depend on whether you're asking how many SQO instructions or how many unique Control tags in those SQO instructions are needed.

If you are using RSLogix5000, I'm pretty certain SQO instructions can handle 32-bit (DINT) tags. In 5 & 500, you're definitely limited to the 16-bit integers.

Also, check out the RSLogix5000 (or your programming software) help section for info on the SQO instruction. This may benefit your understanding of sequencers.

 

[awmiller42]

sorry guys for the lack of information, but that is word for word what my teacher asked, ill defiantly be sure to clarify in the future. i have a few more problems that im currently working on and here in about a hour and a half will be posting pictures of, if you could possibly check back then i would really appreciate it. this is homework/preperation for a test and its going to be the death of me i believe. i love to program plc's, the instruction i recieve though is rough at best at college

 

[daba]

The Sequencer Output instruction SQO can only work with DINT (32 bit) arrays..

So, to create the data needed for your 100 outputs, the minimum number of sequencer instructions needed would be 4, and they would need to "advanced" synchronously (so they keep in step).

That is probably the answer your instructor is looking for, and to be honest, it's not a brilliant question, since it is only asking you to do a bit of math... 100 / 32 = 3.125 so 3 isn't enough, but 4 is.

You will then need to transfer the outputs of your SQO instructions to your physical output modules, especially if they are spread out over the I/O structure. That will involve a bunch of code, possibly using BTD instructions.

It is a shame you are not getting good instruction at college..

 

[rdrast]

And, using the built in SQI/SQO/SQL would be a nightmare here if you need more then 32 status inputs, which is likely with 100 output elements.

I'd say the minimal number of sequencers would be one, and roll my own.

 

[RoTaTech]

If you are using RSLogix 5000, then it is a 32 bit platform.

And, using the built in SQI/SQO/SQL would be a nightmare if you need more than 32 status inputs.

 

[cjd1965]

Hi the op didnt give much info or state a SQO was needed . He did say a sequence was asked.

IMHO Without knowing the task the minimum number of sequences needed would be 1 and the max 100.

This is why a customer should provide a spec