Flip flop or toggle: a rehash

rsdoran · Jan 28, 2003

Please look at this:
http://www.gefanuc.com/support/plc/app00011.htm

I know I have used this before but now it wont work, it flashes the output or doesnt latch properly.

I am not asking how to do this, I want to figure it out myself but trying to understand why it wont work now but did in past.

Steve Bailey · Jan 28, 2003

On rung 4 (the first rung with ladder logic), the coil is one-shot. Its easy to miss that hash mark inside the parentheses. The coil, and any NO or NC contacts with the same address (%M1) will be true for one program scan.

If the coil is not a one-shot, the output will cycle between on and off every program scan as long as the input remains true.

rsdoran · Jan 28, 2003

banghead
WHat a duh, in the process of redrawing and with my eyes the way they are now I did miss the ^ mark which indicates a positive transition coil, dont know why I can not relate this as a one shot, which is what it is.
bonkhead

Eric Nelson · Jan 28, 2003

%I %THINK %IT'S %ALL %THOSE %DAMNED %PERCENT %SYMBOLS %THAT %CAUSE %BLURRED %VISION!...

I guess % was as close as they could come to

in the character map?

beerchug

-Eric

BobB · Jan 29, 2003

Hate the % symbols. Do not particularly like X & Y or I & Q either. Even better how about having to fiddle with 3 registers per timer. How many are accidently overlapped and then you spend days trying to find out why the B***** timer will not work properly.

Goody · Jan 29, 2003

I dont like X & Y for inputs and outputs;

Sometimes, if you are writing your I/O list by hand with a pen, a 'Y' can look very much like an 'X' (the way I write them anyway) and I have found that this can lead to mistakes when writing the symbol (comment) list from your piece of paper into the plc.

And I dont care much for I & Q either, they can look like 1's & 0's

Is there any PLC that has better unmistakable Input & Output letters?

Eric Nelson · Jan 29, 2003

BobB said:
...how about having to fiddle with 3 registers per timer. How many are accidently overlapped and then you spend days trying to find out why the B***** timer will not work properly

I'll admit, this has tripped me up once or twice (in other brands as well). What's more annoying is having to assign the registers in the first place. It's just a timer, so just give me a timer number!...

To make life easier, I usually set aside 4 registers for each timer.
I have a hard time keeping track of "multiples of 3"...

beerchug

-Eric

Peter Nachtwey · Jan 29, 2003

Try Siemens in German

Goody said:
I dont like X & Y for inputs and outputs;

Is there any PLC that has better unmistakable Input & Output letters?

They use E and A for eingang(inputs) and ausgang(outputs).
Do you like that better?

glaverty · Jan 29, 2003

Yeah the %, I, Q, R, N, T, and other letters really annoy me too. Almost as much as all those smiley faces on message boards.

Flip flop or toggle: a rehash

rsdoran

Lifetime Supporting Member

Steve Bailey

Lifetime Supporting Member + Moderator

rsdoran

Lifetime Supporting Member

Eric Nelson

Lifetime Supporting Member + Moderator

BobB

Lifetime Supporting Member

Goody

Member

Eric Nelson

Lifetime Supporting Member + Moderator

Peter Nachtwey

Member

glaverty

Member

Similar Topics