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Old May 3rd, 2003, 06:09 AM   #1
United States

tlvaun is offline
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Join Date: May 2002
Location: Tennessee
Posts: 38
Maintenance alarm (again)

I posted a topic on a maintenance alarm system a few months ago which didn't quite work out, but now have a different project with it all together. I'm going to be adding a touchscreen (Mitsubishi F940GOT) to the system and changing the plc because currently it has 2 seperate plc's and neither is compatible with the touchscreen. I would like to simplify the code. First let me explain how the system works now.

Operator turns on a switch a light begins to flash in the shop (they are a total of 42 different lights) and a buzzer goes off with the light for 3 seconds. After that 3 seconds is over if they turn it back off they must wait 1 minute to turn it back on if they want the buzzer to sound again (this is to keep them from annoying us ). If the light is on for 15 minutes it will stay on solid. The powers that be want me to keep the conditions the same. I was able to shorten down the original version slightly. Here is a sample of my code.

x0 m9020
1st alarm I alarm flicker I 1st alarm lamp
I C0 I
15 minute alarm latch

x0 t0 t30
I 1st alarm I buzzer stop unlatch alarm 1 latch
I I alarm 1
I m0 I
I----11------I----------------------------(t0 k30)
alarm 1 latch buzzer stop

----1/1-----------------------------------(t30 k600)
1st alarm Unlatch alarm 1

x0 m9032
----11----------------11-------------------(c0 k900)
1st alarm 1 sec flicker I 15 minute latch
I for alarm 1
I----------[incp d5]

----11-------------------------------------[rst c0]
unlatch alarm

y40 t0
1st alarm lamp alarm 1 buzzer
buzzer stop

The plc I'm using is a Mitsubishi A1S model. This seems like a lot of code (remember I will be repeating this 41 more times) especially since it will be so repetitive. I've looked through the manual several times looking for a "magical" instruction to solve the issue. Don't get me wrong I don't care to write out the program this way I was just hoping to learn something.
For the touchscreen logic I plan on splitting it out in 3 pages for different areas of the plant and recording time in minutes and occurences. For each line something like this:

----11---------------------------[div c0 k60 d10]
always on bit I current downtime display
I---------------[div d5 k60 d12]
total downtime display

----11---------------------------[incp d14]
alarm 1 occurences

By using division I will be using 2 data registers for 1 because of the remainder factor and remember this will be repeated 41 more times. I would also like to create a screen that would show which alarms were on currently and there downtime data, then remove them when turned off, but I cannot come up with a way remember I'm just a mechanic. Any suggestions, critisisms welcome.

Last edited by tlvaun; May 3rd, 2003 at 06:13 AM.
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Old May 4th, 2003, 04:54 AM   #2
United Kingdom

michael59 is offline
Join Date: Dec 2002
Posts: 19
the 15 minute (co k900) latch is that a timer or a counter your using
on the first rung
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Old May 4th, 2003, 07:11 AM   #3

JvdV is offline
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Join Date: Apr 2003
Location: Halsteren
Posts: 95


Mechanics are probable the best programmers. When they know something about electricity and automation.
Normally mechanics have a good inside how a machines work. And than writting a programm for that machines makes it relatively easy.

But back to your programm.
You want to keep track of the fault messages as wel.
You can do that in two different way's. First of al (and proberblay) the best way. Is to use the error list of the terminal. I don''t know the terminal you are using but most of the new pannels have such a screen.
The second best option is to keep track of the faults in the PLC. This take's a lot of programming. Especially when you want to record the down time with that fault message.
I would use regestries and than move them along as a new error accours.

Maybey a small tip for the fact you have to do 41 times the same.

There are instructions that work with V and Z factors. With these instuctions you can make your programm indexed.
When there is a fault in the programming code it's very difficult to trace it !!!!! Especially when you are new to programming mitshubishi I wouldn't recomend it.

It's also possible to use jump instructions. When you use a small sub routine where you jump to every time you want to do the same. In youre case 41 times. Before the jump instruction you copy the value's you want to registers and merkers then you make the jump.
When the subroutine is finished you copy back the value's to your original programm.

When you use this the first time it's pretty difficult. But it's easier to moinitor when something goes wrong.

Good luck to you. When you need some accamples please let me know.

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