Allen Bradley Question

Hello, Can anybody help me please?
I'm just starting out and trying to learn and use Allen Bradley SLC 500. I'm working on a project to clean Teflon filter bags in a power plant that cleans emissions before being released to the atmosphere.We have 4 Hoppers (each containing a pressurised manifold), from these hangs a boom with a row of filter bags hanging underneath. Each filter or bag has a dedicated Solenoid that pulses a gas .25 of a second approx, in carousel fashion (ONLY ONE PULSE AT ANY GIVEN TIME).Hopper 1 sol1,Hopper 2 sol 1, hopper 3 sol 1, hopper 4 sol1 and back to hopper 1 then sol 2and so on until the 16th sol has completed and then back to Hopper 1 sol1 etc..
The pulse routine works fine. Also an Initialisation and a band routine have been written. I have had help with these.
Now heres my problem!
I have to write an alarm routine.The alarm will be via a HMI panel, with audible and visible alarms Latching with p/button reset.The alarm shows when a Bag (filter) has burst, and needs replacing. This is detected by a drop in pressure via a pressure transmitter attached to the pressurised manifold.The hopper then has to be Isolated and and a new bag fitted, (only 1 hopper can be isolated at any one time). Please advise.
I really dont know where to start, I'm a novice so Please dont get too carried away. I understand the electrical side so the process is understood its the logic code that i'm in the dark with. Many thanks.

There is a free tutorial available here:

http://www.plcs.net/contents.shtml

Otherwise I suggest you hire someone with experience and then study what they've done after they've completed the project.

Thanks for your reply, I'm training (unpaid) at an old company where ive worked before as an installation engineer. I'm recovering from a broken back so cannot do any physical work again so i've turned to software. I'm writting code now but unfortunately everyone in the office is away for 10 days. So as you probably see i'm trying my best and want to show willing. Thanks

I understand your situation (though I'm unsure about not being compensated). Its a good time to turn your unfortunate circumstances into a opportunity. Will your "employer" pay for some training? If so, get in as much as you can. A-B has training courses though I'm not sure of their availability in your location.

Are you using an analogue pressure sensor?
Are you monitoring the pressure at the manifold of each hopper?

The goverment are helping me out and my ex-employer has given me an office to use. Luckily AB/Rockwell are very close to me and have courses booked. but as im sure you understand im bursting with enthusiasm after 2 years of horrific pain and slow recouperation, also of course my financial needs. My courses start in June. Im trying to play catch up and learn as much as possible before starting. Im reading and checking out sites all day.Ive got RSlogix 500 software and emulator and plcs. So im trying to learn quickly but as i said before all the software guys are out for 10 days or so. So im going it alone so to speak.
Thanks for your interest. If i can view other programmes i can decipher the code myself i just need access. Cheers.

Yes i'm using an Analogue input from a manifold pressure transmitter.
Yes each manifold pressure is being monitored independently ,a short drop in pressure will occur when each solenoid activates the gas pulse.So not to drop the pressure too much the solenoids are carouseled to each hopper to give the manifold time to stabalise and keep a more even pressure. Thank You.

Also the Pulse routine is incremented according to the condition, quality of the gas. The dirtier the gas the quicker the routine will pulse each bag, and of course the cleaner the air the slower the pulse thus providing efficient Gas Flow and motor speeds pulling cleaned gas away will be more stable and controlled efficiently.
Thanks

I would think this would be relatively straightforward. Monitor each pressure transducer. If the pressure is lower than whatever the right number is for more than say 2 seconds or whatever time you want than set a bit. Use that bit as your alarm and use the bit in your sequencing logic to prevent it from being cleaned.

TO expand on Brian's answer, he wants you to use an LES function to determine when the pressure is low. The right side of the rung will have a coil OTE that "sets a bit". The contact XIC can set an alarm coil (bit) and you can use a normally closed contact (XIO) to disable the cleaning.

Get your hands on the A-B Refernce MAnual for the SLC and MicroLogix Instruction Set, PN 956500-02. It has good examples and will help you tremendously in understanding the concepts. Also, get Phil's book, and read the tutorial on this site.

To further expand on the previous posts:

etc...
Something like this is what you're looking for...
Put your clear alarm logic immediately before the bit setting logic, NOT after. This way, if the operator tries to clear an alarm while an alarm condition still exists, the bit will immediately re-latch.
Paul C.

trying to learn and use Allen Bradley SLC 500.

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ok ... but not very specific ... see below ...

My courses start in June. Im trying to play catch up and learn as much as possible before starting.

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excellent plan ... we’ll try to help as much as we can ...

i'm using an Analogue input from a manifold pressure transmitter

Click to expand...

what type of signal? ... 4 to 20mA? ... 0 to 10VDC? ... other? ...

Ive got RSlogix 500 software and emulator and plcs.

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here’s where we REALLY need the specifics ... give us a FULL list of the actual hardware that you can put your hands on and PLAY with ... use the catalog numbers (example: 1746-IA16) ... then tell us EXACTLY how your hardware system is plugged together (slot-by-slot) ... once we have that information, then we can give you SPECIFIC answers with addresses, etc. rather than just general advice ...



if you have limited hardware and plan on using the emulator for your exercises, that’s ok too ... but we need to know about that ... there ARE some differences between the way the hardware and the emulator work ... not knowing those differences can lead to a LOT of frustration and wasted time ...



also ... learn how to post your PLC code on the forum ... Phil’s “Practice Posting Here” section is great for that ...



remember, the more we know about your efforts, then the more help we can provide ...



these links may help ...



SLC-500 Instruction Set Reference Manual



SLC-500 Modular Hardware User Manual



RSLogix500 Getting Results Guide



I wish you the best of luck ...

Numb,

1st off, Glad you are recovering well. Like mentioned above, cut/pasting of your code will help not only us but you in long run.

One other thing, since you are just starting, just look at the picture as being ONE hopper first. Get it working/programmed first, then you can add the others. Some people just starting out get overwelmed with the 'whole' picture.

good luck,