carwash plc

[ACHIAPPETTA]

hey great site, first time here.
i think i bite off just a little to much, great at trouble shooting just never wrote a program.

the plc is a idec microsmart fc4a-c16r2. there current plc is a mac 3000 by mcneil ind.

what is wanted is to use the idec as a stacker for 8 cars with 4 types for washes to feed the selected wash to the mac 3000 when the car crosses an eye sensor.

the mac is and single input per wash cycle plc. so car A has to complete the cycle thru before the next can enter.

i was going to use the shift register to accomplish this but thats is where i am lost.

Idec has been no help what so ever, can any one here help?
thanks
anthony

 

[milldrone]

what is wanted is to use the idec as a stacker for 8 cars with 4 types for washes to feed the selected wash to the mac 3000 when the car crosses an eye sensor.

the mac is and single input per wash cycle plc. so car A has to complete the cycle thru before the next can enter.

i was going to use the shift register to accomplish this but thats is where i am lost.

Idec has been no help what so ever, can any one here help?
thanks
anthony

Anthony,

Welcome to PLCs.net!

I'm going to make some presumptions here.

1. The Mac 3000 as some inputs (buttons on present panel) that you want to energize with outputs from the Idec PLC. Correct?

2. You want to store up to 4 different "wash cycles" and assign them to a car. And you want to store up to 8 cars with different wash cycles. For instance you want wash cycle "a" to be assigned with car #1. When car #1 gets to the photo eye you want the Idec to energize the "a" button on the Mac3000 panel. How am I doing?

If this is what you want. Then you want a FIFO. First In First Out. Not a shift register. A FIFO can have a variable number of cars in the "stack" a shift register has the same number of cars in the "stack" at all times.

Note: I have zero experience with an Idec PLC

 

[milldrone]

ACHIAPPETTA,

I forgot to also mention that a shift register cannot store 4 wash cycles either a shift register (bit) can only be off or on.

I looked up your model of CPU and it does not support a block move. It does how ever support a indirect move This must be Idec's version of a pointer.

I think this member is an Idec guy
http://www.plctalk.net/qanda/member.php?u=31074

 

[Stationmaster]

Mildrone is correct, I do work with IDEC PLCs. I don't know a lot about car washes though.

I'll be glad to help, but we will need to know specifically what you are doing. Start by answering the questions Mildrone posed.

From your post, and Mildrone's analysis, it would seem that you need a data register per car. That you'll input data into the most recent data register that will be interpreted as 1 of 4 washes in the form of 1 of 4 outputs from the IDEC, and then 1 of 4 inputs to the Mac 3000 (ALSO something I know nothing about.)

I do work with photo controls, and I see that you'll be "shifting" to the next register each time a car passes yours. You'll want to use a time delay of about .4 or .5 seconds to take the "bounce" out of the photo control.

How will the 1 of 4 wash types be entered into the PLC?

I'm in the process of moving, so finding my Microsmart book may be a challenge, but I'll give it a shot.

Stationmaster

 

[ACHIAPPETTA]

questions answered

thanks for all the responses

the way i have envisioned this is that the idec will be connected to the 4 wash types on a button board.
then attendent will set car 1 for the plus (#2) carwash.
when that car hit the eye beam athe idec it close a contact and send 12 volts to the the macs plc input 2, then clear its self for the next car which by now would be sitting at the red light waiting for car 1 to clear the tunnel while the attend "stacks" the following cars behind car 2.
i hope this make it a little clearer.....

milldrone has the gestof what i want to do. now to explore FIFO, are there any demos of how the FIFO works, the tutorial from idec doesnot have any info on fifo.

thanks
anthony

 

[Stationmaster]

Anthony,

A "FIFO" is nothing more than a series of D registers that are treated in a particular way. The operator loads data into the first register and and the next data entry goes into the next register and so on. As some task is completed, (the car going past the photo eye for example), the data in the first register is used and then discarded. Then the data in the second register is moved to the first, the data in the third data register goes into the second, the data in the fourth register goes into the third and so on..... IDEC's way of accomplishing this is to use the "mov" instruction. The "mov" instruction has a "repeat" feature that allows multiple series moves.

You still haven't told us how the data will be entered into the PLC....

Stationmaster

 

[ACHIAPPETTA]

ok please bare with me , i am electricial with "some" plc experience, most ladder trouble shooting.

i look at the ladder print out and figure where the problem is and fix the part that is not working, but have learn alot just playing with them.
to answer your Q, the idec will send the first cars selection to one of the 4 inputs on the mac plc, just like pressing the button, it sends the 12 volt power to this input on the mac plc, button closed send 12 volt to input on the mac plc, the idec will replace the button in this case, make sense?
its late, mayeb i am not making sense. we are relocating the 4 possible selections to a farther location, with memory so more cars can line up.

does this help?

 

[BITS N BYTES]

Your best bet is to use the WSFT [WordShift] instruction.
You have 4 types of wash each defined by one of 4 pushbuttons.
When you press button 1 move a value 1 into the WSFT.
Button 2 move value 2......

That puts the required group of washes in order into memory areas. You also to increment a counter [offset pointer] to store how many records have been input with WSFT.

The next step is how to get a wash record using First IN First OUT [FIFO]when a car enters the wash.
If there are 8 records then when you start the next wash you will need to get the record from the 8th location.
For this you use the IMOV [IndirectMove] instruction with an offset of 8 and decrement the counter.

The challenge is making sure that WSFT and IMOV are correctly coordinated with the counter [offset pointer].

My 2 cents.

 

[Stationmaster]

ok please bare with me , i am electricial with "some" plc experience, most ladder trouble shooting.

i look at the ladder print out and figure where the problem is and fix the part that is not working, but have learn alot just playing with them.
to answer your Q, the idec will send the first cars selection to one of the 4 inputs on the mac plc, just like pressing the button, it sends the 12 volt power to this input on the mac plc, button closed send 12 volt to input on the mac plc, the idec will replace the button in this case, make sense?
its late, mayeb i am not making sense. we are relocating the 4 possible selections to a farther location, with memory so more cars can line up.

does this help?

I think I pretty well understand how the IDEC PLC signals the MAC 3000. What I'm ASKING is this: "How does the operator put the information into the IDEC?"

 

[ACHIAPPETTA]

stationmaster,

the attendent will press the button to select the was like previously, but in a remote location, 80 ft from the beginning of the lane while taking your money

 

[Lancie1]

If there are 8 records then when you start the next wash you will need to get the record from the 8th location.

If there are 8 records in an actual FIFO register, and you want to start the NEXT wash, then you will need to get the record from the FIRST location. Remember it is "first in, first out" not "last in, first out". But then the Wordshift command is not a true FIFO.

The Idec Wordshift command only shifts data up in 16-bit increments. It does not have the usual FIFO instruction feature that unloads in the same order as it was loaded. So if you use it, you must know before hand how many cars will be in the line. That is not possible in the typical car wash, because more cars can come in at any time (while the first one is being washed).

I think it will take some fancy (but not imposible) programming to implement a FIFO using the WSFT (Wordshift) command.

One possible method:

1. Determine the maximum number of cars that can physically get in the line waiting to be washed. Call that number M. For example, say M is 10 vehicles.

2. Set up memory locations for 10 words, call it Q-data. The Q-10 position will be the "Wash" position.

3. Each time a car enters the wash, determine how many are left waiting (say it is 3). Call that number "W". Sutract W from M: 10-3 = 7.

4. Shift the data in Q-data (M-W = 7) to get the next car into Wash position.

It will take a bunch more finalging, but that is a start.

 

[ACHIAPPETTA]

ok... well i can see that this is well outside my knowlage base.
like i said in my first post, " I think i bite off more than i can do".
so with that said, is there anyone that is will to take on a project?
i can get you the iso for idec development package that i have been trying to build this on, as a consulitant?
i can see that i will not meet my deadline on my skills.
if so send me an email or pm.....
thanks to all that have helped
anthony

 

[Stationmaster]

As others have pointed out, there are many approaches to loading the data into the first empty register, shifting that data along one slot at a time as triggered by the photo eye, and using it to select the correct wash at the Mac 3000.

Not to be contrary, but for a beginning programmer I would still recommend defining your 8 data registers and using the plain ol' "mov" instruction to move the data along as required..... Each time you shift all the data sets to the next set of registers, you just shift zeros from a ninth register into the eighth and shift the zeros along each time a car gets washed. when another car pulls up, the selection for that car is loaded into the first register with zeros.

The BIGGEST issue I see is that with up to 8 cars stacked up, and human nature being what it is, there will be (1) errors in entering the data and (2) customers who change their minds. Both of these will require giving the operator the ability to CHANGE a selection AFTER the fact.

I personally wouldn't tackle a project like this without a minimal touch screen to identify the car with it's selected wash option, and the ability to correct that selection for each car. That is, you would always be able to see what was in each of the 8 registers, and make changes to that data.

One example would be a false trigger of the photo eye, soap suds, employee walking by, a bird flits past..... However it happens, the stack will eventually somehow get out of sync. Unless you want up to 8 cars, each getting the wash intended for the car behind it, the operator is going to have to have more control than just selecting one button per car one time and living ever after with THAT selection.

There will be MUCH more programming involved to set the whole system up in a way that you can continue to have control over the selection, than to just make a series of selections and shift the data along.

Stationmaster

 

[ACHIAPPETTA]

Stationmaster thank you for your input.
as i have figured out i am a beginner, i realy thought i could just sit down and hack this out, hey i have 25 years experience with computer and similar thing... but i am wrong. i do miss the days of basic haha

anthony

 

[Controls_Engineer79]

if the customer was willing to go with a allen Bradley series plc then i would be more then happy to take on the programing for this project - - - as i remember doing a palletizer application that seems similar to this. We had pallets coming down a conveyor into a robotic work cell where they would line up awaiting a worker to enter in on a panelview the type and colour and application pattern of stretch wrap material that could be applied - the user could enter up to 8 configurations in advance - with any combination of patter - colour and type - per unit. the system was controled using a FIFO that fet into the group and digital IO of the robot- the user could also use the panelview to monitor what orders had been entered and could select and del any incorrect ones as long as the machine hadnt reached the incorrect order. the user could also add more orders to the waiting list on the fly as the system was running - up to a max of 8