Turning on motors in sequence using indirect addressing.

So I have a problem that I am trying to overcome. I have X amount of motors (I'm trying to make the program scaleable). Let's say that a system has three motors. Each motor has a Hand/Off/Auto setup. I need the motors to start in a sequence. The outside program should read the sequence and turn on each motor individually as the conditions occur to make them do so.
Here is the real thorn in my side. The motor sequence is decided by a few things. The PLC is recording the hours that the motor gets run, so I want to start the first one if it has the least amount of operating hours on it. If system demands are too much after a fixed amount of time, then the second one with the second least operating hours comes on.
The second thorn in my side is that since each motor has a Hand/Off/Auto function, the sequence should skip over whichever motor is not in auto, but have the very next one come on at the second condition that is stated.

I'm using the Automation Direct Do-More series CPU. I'm 90% sure this can (and should) be done with indirect addressing and possibly casting, but I am having a difficult time piecing this one together.

Any advice is much appreciated.

-TL

Equalizing pump hours can lead to all pums to fail allmost same time.
However, Ron have maded example of 12 fans rotation. It is indirectly programmed, so it can examped easily.

You need two differend order groups. First one is pump run times (compare all pumps). After you have ordered pump runtimes, then look only available pumps, and make another order group. (Move zero or big number for pump, which is not available, and order pumps again)

http://www.plctalk.net/qanda/showthread.php?t=49120
http://www.plctalk.net/qanda/showthread.php?t=51640

Lare said:

Equalizing pump hours can lead to all pums to fail allmost same time.
However, Ron have maded example of 12 fans rotation. It is indirectly programmed, so it can examped easily.

You need two differend order groups. First one is pump run times (compare all pumps). After you have ordered pump runtimes, then look only available pumps, and make another order group. (Move zero or big number for pump, which is not available, and order pumps again)

http://www.plctalk.net/qanda/showthread.php?t=49120
http://www.plctalk.net/qanda/showthread.php?t=51640

Click to expand...

This looks to be exactly what I needed. Thanks.

For pump amount up to 4 or 5 programming is not too bad if you simplify code with Karnaugh's map. (16 or 32 dfferent sequences)

Indirect is good for 6 or more pumps.

Lare said:

For pump amount up to 4 or 5 programming is not too bad if you simplify code with Karnaugh's map. (16 or 32 dfferent sequences)

Indirect is good for 6 or more pumps.

Click to expand...

From the post by Ron, I really like the cleanliness of the programming. Now, what I need to find is a clean way to pack up my hourmeter compare lol:book:

This should work, just make sure that index is allways between array start and end values. If you PLC have array sorting, min and EQ comparing, comparing goes easy.

if clock_pls then             (* "1" state several PLC cycles *)



if index<=10 then            (*increment hourmeter if pump is running. Increment is done only one time/Clock pulse*)

if pmp_run_array[index] = true then

pmp_hour_meter_array[index] := pmp_hour_meter_array[index] +1 ;

End_if;

index:=index+1;             (* increment index value *)

End_if;

End_if;



if Not clock_pls then            (*zero to index*)

index:= 0;

end_if;



if index <0 then            (*init index counter*)

index:=0;

end_if;