A plea for help...and mentor

[damianjones]

Hello All,

As part of my I/O Audit I've found there is not a sensor on the main fan/blower. Does anyone have a recommendation where I can purchase one?


Thanks,

Damian

 

[Tom Jenkins]

You didn't identify what type of sensor you need. For fans/blowers I usually monitor motor amps, but you may or may not need pressure sensors, flow sensors, etc. You're original logic description didn't have that info either, and I confess I haven't opened your logic file.

I do suggest you go to Omega Engineering and look at the types of sensors they have. http://www.omega.com/ They don't make a lot of the stuff themselves and you can usually buy it cheaper, but they are hard to beat for one stop shopping on a one or two item purchase, and they have some great tech info in their catalogs.

 

[damianjones]

Hi Tom,

I don't really know what type of sensor I need. I'm hoping to describe the situation to the sales engineer to direct me in the right direction.

Thanks for the link. I'll go check it out.

Damian

 

[MarkTTU]

We use a 0-2" WC transducer that gives a linear 4-20mA output on all our new products. Very slick and they make various pressure ranges. The company we get them from is Dresser Instrument 203-385-0253.

We also use a mechanical differential pressure switch from Dwyer Instruments in Michigan City Indiana, their number is 219-879-8000.

If I read what you need correctly you just need to know that the fan is still moving air, if that's the case get a pito tube assemby and pressure switch from Dwyer, it'll be alot cheaper.

 

[damianjones]

Hello All,

Here is the latest news. The Maint Supervisor and I went out and audited the I/O. After me assured me that everything was working we get the PLC plugged into the laptop and almost nothing matches up. Very tactfully I suggest we have everything looked at and find out who installed the system.

I did download the information for the PLC into the laptop. As you can see there is very little in documentation but it seems simplier. I'm working on getting everything documented.

Thanks again,

Damian

 

[damianjones]

sorry, forgot the sheets I found in the PLC casing...not too helpful since nothing matched up....

 

[damianjones]

Sorry Guys,
My brain must be fried. I forgot to send you the update drawing of the system. The Maint. Supervisor explained the outside blower (previously described by me as the TRUCK FAN) is a closed system. There is an airlock (Previously described by me as dust tower fans) on each dust tower that allows the dust to pass through but keeps the air out.

 

[martyh]

So, If I look at all the posts you've done so far, and try to
figure out the plain and simple explanation of what's going on
here, would it be that:

You have two "Dust Towers" (Baghouses?) that pull dust-laden air
out of a building. These dust towers probably have their own
internal timing card to pulse the bags/shake them/whatever...
Then there are air locks on the hoppers for the towers (probably a
rotary air lock), which USED to dump the dust in to an auger and
convey it to some point.

And I assume that now you want to use a blower, rather than an auger to convey the dust to a rollaway hopper ("truck fan"), which can be hauled away when it gets full.

Correct?

 

[damianjones]

YES!!!
That is it on the nail. Things have slowed down since I found out either the PLC is not installed properly or (I'm leaning to this side) somehow I didn't test correctly. I will retest soon as I figure out what I did wrong. I tested the inputs by pressing the on and off buttons and notice it lit up on PLC, but I didn't see change on the data table.

Am I correct in assuming if I were to connect to the PLC and go online in the program. Then open the INPUT data table: When I press the on button I should see a bit on the table change either from 0 to 1 or 1 to 0?

The same on the out put table, but here if I change a bit from 0 to 1 the device connected to the PLC should turn on?


Thanks all,
Damin

 

[harryting]

...

Am I correct in assuming if I were to connect to the PLC and go online in the program. Then open the INPUT data table: When I press the on button I should see a bit on the table change either from 0 to 1 or 1 to 0?

...

You are correct, the LED responds so that's a good sign. Are you SURE you are online when you were doing this? Is the little ladder spinning in RS500?

 

[Ron Beaufort]

Greetings Damian,

Am I correct in assuming if I were to connect to the PLC and go online in the program. Then open the INPUT data table: When I press the on button I should see a bit on the table change either from 0 to 1 or 1 to 0?

basically, yes ... but with the MicroLogix 1200 that you are working with, the processor MUST be in the RUN mode for this to work ... in other words, the processor does not “read” inputs from the field unless it is in the RUN mode ...

The same on the out put table, but here if I change a bit from 0 to 1 the device connected to the PLC should turn on?

basically, yes ... but again, the processor MUST be in the RUN mode for this to work ... in other words, the processor does not “turn on” outputs in the field unless it is in the RUN mode ...

further ... IF you put a “1” on the output table ... AND the “1” stays there, then the field output should come ON ... but ... IF you put a “1” on the output table ... AND the “1” does NOT stay there (specifically it changes right back to a “0”), then the field output will NOT come on ... this “the-1-won’t-stick” effect will occur because something in your existing program is “controlling” the bit and turning it right back OFF again ... in that case you (the human) need “more power” ... you can use a “force” to override the ladder logic program and “force” the output come on in spite of the ladder logic program ...

now ... while all of this “pressing of the buttons” and “changing of the output bits” activity is going on, keep an eye on the little LEDs on the front of the processor ...

basic idea for inputs: pressing a button in the field SHOULD make the appropriate LED go OFF and ON ... if it does NOT do this, then the first thing you should do is check the field wiring, button contacts, etc. ... now you MIGHT CONCEIVABLY have a bad input on the MicroLogix ... but ... chances are that there is something wrong in the field ... specifically ... if the LED does NOT light up on the MicroLogix, then don’t waste your time looking at the Input Table with the software ... nailed down: if the LED doesn’t see the input signal, then the processor can NOT see it either ...

basic idea for outputs: forcing an output OFF and ON with the software SHOULD make the appropriate LED go OFF and ON ... if it does this, then you can expect the field device to go OFF and ON too ... if the field device still does NOT go OFF and ON, then the first thing you should do is check the field wiring, output device, etc. ... now you MIGHT CONCEIVABLY have a bad output on the MicroLogix ... but ... chances are that there is something wrong in the field ... specifically ... if the LED lights up on the MicroLogix, then don’t waste your time looking at the Output Table with the software ... nailed down: if the LED comes ON, then the processor is doing everything in its power (bless its little heart) to turn the field device ON ...

sorry I haven’t had time to download ANY of your programs ... work is pressing ... and ...

DISCLAIMER: I haven’t had time to proofread the information I’ve posted above ... but if I’m wrong, then somebody will probably correct it pretty soon ... sorry if I dropped a stitch ... got to get back to work ...

 

[damianjones]

Hello All,
Solved the problem with the I/O ports on the PLC. Turns out the latest program in the PLC was not the right one to use, and more importantly I don't think I had it the application set up correctly. Once sure that everything was in place (took me about 20 minutes before I could get the alarm light to flash) I went about auditing the I/O ports. I still need a sensor, my boss was to go with a current sensor for the OUTSIDE_BLOWER which would tell me if the motor is off, but I would like something to tell me the outside pneumatic conveying system is outside of recommended parameters. What are your thoughts?

Here is the latest program. I need to add a 2nd alarm light for system 2. what I would like is when part 1 of the system goes "down" then alarm light 1 flahes, and the same for part 2.

I don't really like the jumping to different ladders. Is this standard operation? Is there any points of the program I should look out for?

As always, eternal thanks.

Damian

 

[mordred]

could you plz post an output list for your SQO statements.

 

[damianjones]

Sure.....um how do I do that?

 

[Ron Beaufort]

Greetings Damian,

just time for one quick question:

I don't really like the jumping to different ladders. Is this standard operation?

yes ... most programmers would do it this way ... the basic idea is that if you're working on "System B" then you shouldn't have to keep scrolling up and down past the "System A" stuff too ... most people think of the different ladder files as something like "chapters-in-a-book" ... it just helps to organize the code into functional sections ...

but ...

if you don't like it, you don't HAVE to use it ... just "cut" the rungs from the "extra files" and then "paste" them over into ladder file #2 ... then delete the JSR instructions to clean things up ... the processor doesn't really care how disorganized the program is ... he'll scan your code just fine even if it's all located in ladder file #2 ...

once again, I'm sorry that I don't have time to take a look at your program ... work is keeping me very busy right now ...