ON/OFF output using PB in Auto/Manual mode

ckchew666 · Jun 17, 2005

Hi,

I'm working on a program where the condition as below:

1) Auto Mode (Maintain Push Button) - When pressed = Auto mode, if not pressed = Manual mode.
2) Auto Start (Maintain Push Button) - when pressed during auto mode, energize output (fan)
3) Fan ON (Momentary Push Button) - When pressed during manual mode, energize output (fan)

All the PB is in the Touch Screen
Attach is the logic that I've written, is there any better/simplier logic than this?

Thanks.

Regards,
CK Chew

Eric Nelson · Jun 17, 2005

The end result is all that really matters, but if you want another idea...



|  Fan ON                        1-SHOT

|---] [----------[OSR]-----------(   )

|

|                       AUTO

|  1-SHOT    TOGGLE     MODE     TOGGLE

|---] [-------]/[---+---]/[-------(  )

|                   |

|  TOGGLE    1-SHOT |

|---] [-------]/[---+

|

|   AUTO      AUTO

|   MODE      START                FAN

|----] [------] [---+-------------(   )

|                   |

|  TOGGLE           |

|----] [------------+

-Eric

chavak · Jun 17, 2005

Just to fullfil your conditions, here is another method

chavak · Jun 17, 2005

Sorry, my image didn't appeared, trying again

DanielCamacho · Jun 17, 2005

Nice but....

chavak said:
Just to fullfil your conditions, here is another method

In manual mode the only way to turn off the fan would be to switch to auto and provided that the auto start PB is not activated.

The other problem, if you stated in auto and remove the auto button the fan continues to run. Not sure thats a good idea...

I would try out Eric's method it makes your Momentary Fan button toggle your fan on and off in manual mode, with out interferance with the other buttons...

trojan_goat · Jun 17, 2005

ck, this will work also...

trojan_goat · Jun 17, 2005

Ok,

DanielCamacho · Jun 17, 2005

Sorry but no....

Trojangoat, that will not work... the fan will never come on in manual mode. Second, in auto mode, if you take it out of auto before you turn off the auto start the fan will stay on...

trojan_goat · Jun 17, 2005

Well Daniel, your right about the Auto, I left out one thing, but fixed it....here you go ck.

Eric Nelson · Jun 17, 2005

trojan_goat,

Based on ck's description (and existing logic), the manual fan PB should toggle the fan on and off in manual mode, regardless of the auto start PB's state.

-Eric

DanielCamacho · Jun 17, 2005

Yes...

trojan_goat,

Yes that does work now, and it also toggles the fan on and off in manual mode...

DanielCamacho · Jun 17, 2005

ckchew666...

Just checking your code a little more in depth, and found that your B3:1/12 bit does not get unlatched when the the PLC is placed in program mode and then returned to run. In other words your fan will start up again with out pushing any button if that bit is latched... Again take a good look at the code provided by Eric, this is very solid...

Or and this above your first rung:



        First Pass                   Toggle

Rung 1 -----] [------------------------(U)------ 

          S:1/15                     B3:1/12

Terry Woods · Jun 17, 2005

Curious...

B3:1-14 is named both, Manual Mode and Auto Mode.

Is it the case, in this PLC, that one can provide different names for the different states of the same bit?

That is...
B3:1-14 as --| |-- is "named" as "Auto Mode"

While...
B3:1-14 as --|/|-- is "named" as "Manual Mode".

Is this so?

darrenj · Jun 17, 2005

Terry Woods said:
Curious...

B3:1-14 is named both, Manual Mode and Auto Mode.

Is it the case, in this PLC, that one can provide different names for the different states of the same bit?

That is...
B3:1-14 as --| |-- is "named" as "Auto Mode"

While...
B3:1-14 as --|/|-- is "named" as "Manual Mode".

Is this so?

Wow..good call terry..i am curious about this now..i didnt think it was possible..

rsdoran · Jun 17, 2005

Actually I dont like any of these, makes it all seem complicated. The problem is I understood what was done. PB B3:1/14 is actually named PV_MODE_PB, the YELLOW background part is descriptions which in this case show what is happening...ie if 0 then its Manual, if its 1 then its AUTO. The AUTO MODE should not be there, it confuses the descriptor. Its common for me to find a selector switch or maintained pushbutton with just one wire going to a plc input in this fashion...ie when its on it does one thing and when its off it does another.

The original descriptions confuse some of this. To me this is all to complicated for something simple. The following I have done, if in automatic the fan will start and be latched in but has stop PB, if in MANUAL (AUTO is FALSE) then fan will run as along as START PB is held in.

 

     Stop   StartPB          Fan

|-----| |--+---| |-------+---( )-|

|          |  Fan    Auto|               

|          |---| |---| |-|

Told y'all I think simple.

ON/OFF output using PB in Auto/Manual mode

ckchew666

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chavak

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