Drum Sequencer Problem

taylor · Dec 7, 2005

This time I did include the file. Sorry about that. Have fun with this one

OkiePC · Dec 7, 2005

My version of Word (Word 97 SR-2) can't make sense of that file...do i need to change theextension to something else? or is it from a newer release?

elevmike · Dec 7, 2005

You need this to read the document: http://www.openoffice.org/... I think.

Taylor, download a free pdf printer here: www.pdf995.com and use it to print out a pdf, then post the file.

panic mode · Dec 7, 2005

you can open it with winzip (header starts with "PK").

you will see bunch of XML files and one picture.
Text is something like this:

Description of the problem
It is required to perform the following using the drum sequencer.
Wait for the start button.
Activate the motor and wait for 10 seconds.
Activate the cylinder right and wait for feedback confirmation.
Wait for 9 seconds.
Deactivate cylinder (move cylinder to left) and wait for 11 seconds.
Deactivate motor and wait for 8 seconds.
Repeat steps 2-6 a preset number of times automatically and then go to step 1.
The preset should be read from the thumbwheel (1 digit) at the start
of the sequence and any subsequent changes to the thumbwheel should be
ignored until the beginning of the next complete sequence.
If stop button is pressed at any time then deactivate all outputs and wait
in the current step for the start button to be pressed to resume from the
current step.
If the jog button is pressed then go immediately to the next step.
WRITE A PROGRAMME THAT WILL DO THE ABOVE
The cylinder's default position is in the left. It can only either be in the
left or right position.
All switches are momentary action.
On completion of this programme you should be able to answer the following questions:
What is the purpose of the full bit? How is it used in this case?
What are the Drx.V and Drx.s words for?
What limitations does the drum sequencer have? Can these be overcome?
What happens to the step time when stop is pressed?
How could you handle more than 1 digit from the thumbwheel?

I don't think this guy is lecturer, he seam to be one of the students trying to get lucky and he is still struggling with basic computer tasks like posting his homework or doing it in same tread...

elevmike · Dec 7, 2005

Taylor,

Have you ever seen the mechanizems of a music box? Ok so it's a little drum with pegs that catch and flick the chimes in a particular sequence to play whatever tune is on the drum. So in the PLC you can have a drum driven by an event, (input from a limit switch or button), or by time.

Let's say you have an 8 x 8 drum, (it's an example guys) so the drum has 8 positions for a full rotation, and 8 possable outputs (or pegs) for each position. So as the drum is sequenced the statis of the outputs changes reletive to where the pegs are on the drum.

For example the zeros = no peg (output off), and ONEs = peg (output on)



 

        outputs: 1  2  3  4  5  6  7  8

 

Drum position 1: 1  0  0  0  1  1  0  0

Drum position 2: 1  0  1  1  0  0  1  0

Drum position 3: 1  0  0  0  1  0  0  0

Drum position 4: 1  0  1  1  0  1  1  0

Drum position 5: 0  0  0  0  0  0  0  0

Drum position 6: 0  0  1  1  0  1  1  0

Drum position 7: 0  1  1  0  1  0  0  1

Drum position 8: 0  0  0  0  0  0  0  1

So output 1 could be "plunger forward", and output 2 could be "plunger reverse" or whatever.. Like I said, the drum positions may be advanced by time or event, (timer, or counter, or external input maybe).

That's about the sum of what a drum sequencer is.

taylor · Dec 8, 2005

Wasters

panic mode if you can't do it then just admit it

Ken Moore · Dec 8, 2005

He did not specify what to use to solve the problem. It would be very easy using a Siemens/TI 505 PLC, since it has a built in drum instruction, looks very similar to Mikes example, only larger, 16 x 16.

My programming experience has been almost entirely TI, AB, and DCS, do any other platforms have "built in" drum sequencers? I am familiar with the AB sequence instruction, but find the TI version more usable, because the instruction has the matrix built right in, easier to set the desired bit conditions. Having everything all in one place also aides trouble shooting.

Just curious,

Ken

rsdoran · Dec 8, 2005

Just another slacker

taylor said:
panic mode if you can't do it then just admit it

You have to be kidding, panic could do this in his sleep
BUT
The precise HOW TO depends on the PLC involved.

Personally I have to agree with panic on this one, this is probably a student looking for someone to do his homework.

If not then what exactly are we suppose to be doing?

Hi, Im a lecturer in control systems working in Germany. There is a file attached to this which includes a simple drum sequencer problem. See what you make of it!

Yep, it could be a drum sequence...maybe.

What full bit?
Drx.V and Drx.s appear to be word address, if correct then what brand. This type question is plc specific and since no brand or program example was given, how can an answer be given?
What happens to the step time when stop is pressed? Whatever you want to happen.
How could you handle more than 1 digit from the thumbwheel? Lookup multiplexing.

My last question.

Wait for the start button.

Where did it go that I have to wait for it?

elevmike · Dec 8, 2005

taylor said:
panic mode if you can't do it then just admit it

That's an unreasonable response. Panic went through the trouble of reposting your criptic file, and I went through the trouble of explaining a drum sequencer in an attempt to start a progressive dialog. Addtionally you posted the same topic to a number of threads, making it more diffucult then necessary to follow.

1) I still dont get the jest of your question. Are you asking for commenets on a proposed assignment? Or do you want to solve the problem?
2) You didnt name necessary specifics, like the plc type which make anything but a very general response, nearly impossable.

3) Just the overall nature of your posts raises suspicions as to your actually being a lecture as you've claimed.

Rod · Dec 8, 2005

Ken,
Several of the ADs have drum. The 06 for sure.

Drum is SO SIMPLE! I'm a Newbie and could write that in about 15 mins on an AD06.

Rod(The CNC Dude)

Drum Sequencer Problem

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panic mode

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