ON/OFF output using PB in Auto/Manual mode

[monkeyhead]

What I don't understand is why all your examples are written using bits only?

Why are all the examples only in bits

hey clint,

for the purpose of examples, bits are easy to work with and convey the intent of using real i/o addresses just as well.

and some programmer's prefer to map all their I/O to bits.

for example:

   I:0/1                  B3:0/1

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

 map an input to a bit

 

   B3:1/1                  O:1/1

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

 map a bit to an  output

 

then use the bit addresses instead of the actual i/o addresses throughout the rest of the program

this offers a huge advantage if an input or output goes bad. then only one rung needs to be changed to re-assign the bad i/o to another location, instead of having to replace every instance of the bad i/o throughout the program.

 

[rsdoran]

As an addendum I have also done "not so simple" or probably convoluted programming along the same lines. The attached are the RSLogix file and 300 Micro Panelview file for a system I did that had the option for manual start or start on selected day(s) at selected times and turned off at selected times on those days.

 

[Eric Nelson]

Based on CK's 'conditions' list, your ladder would be perfect. He mentions nothing about toggling the fan on and off (push on, push off), though in his ladder example he IS toggling the fan output.

Again, we can only go by the information provided. Who knows, this 'fan' may simply be a fan to cool the machine operator...



-Eric

 

[DanielCamacho]

I'm sorry...

I'm just not used to tip toeing around some you old timers here, and yes I am a new guy, however, first Terry; what I meant by dual usage is exactly that, a bit that is USED both ways... I'm sure that most people here know that a bit has two conditions, and I think it was pretty obvious what I was saying... I'm just not sure why Terry, your panties are in a wad over my description philosophy. When that bit is 1 it’s obviously Auto if its not 1 it MUST be 0 or Manual, if the PLC has faulted and the PanelView lost comms, and then the PLC is reestablished that bit will either be set or not BUT it will be 1 or 0, Auto or Manual…
Secondly Ron; that just will not work for his situation, if you look again at the description and his code,

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)

which works by the way, he is looking for a cleaner way to achieve the SAME results. Your code is simple start, stop and jog logic to start the fan; he requires a bit more... Since the "Fan ON" PB is momentary and he is using it to manually start and stop the fan, he needs the flip-flop logic included...

 

[rsdoran]

Wanna know something...I dont like none of these, mine included. Wheres the ESTOP? or something to make it stop if needed in AUTO?

I never give up, I assume that part of the code/conditions could be added. What about this? If its in Auto and you switch to Manual then you should need to Press the FAN_ON PB. IF its in Manual and you switch to AUTO it shouldnt matter if fan still runs.

 

[DanielCamacho]

Well Ron his description was really not all that clear, as stated, but by looking at the logic, he has no stop PB, in manual he is only able to flip-flop the Fan PB or put it in auto without the auto start button engaged to stop his fan... I think your last submission is much better method than what he has, but then again we don't know what he has to work with...

 

[Unregistered]

Thanks Monkey,

That makes sense although it would confuse me at this point to try it in a program.

Clint

 

[mjisaacs]

I found Eric's approach concise, and thoroughly thought out. As a matter of fact, this is how I am now doing a flip-flop with one pushbutton. I have made mods, depending on my program, but it is solid. Siemens makes it easier to do this trick.

 

[trojan_goat]

Wanna know something...I liked mine! It worked! Has everything CK asked for. If he wants to add an E-Stop, he can add it.