Is my math right?

Forshock · Aug 8, 2002

here we go, trying to get this right i want to add 15 to a number in v7770 (Realtime Clock minutes) and store it in v2548 (User storage so i can do:

LD
V7770

ADD
K15
OUT
V2548

and taht should add 15?

PLC: DL05 /w Realtime clock card

Thanks
Mike

Eric Nelson · Aug 8, 2002

DirectSOFT will fight you on this one... It doesn't allow you to ADD a constant. Just swap the constant and variable. Same end result

LD K15
ADD V7770
OUT V2548

-Eric

bubba jones · Aug 8, 2002

It will be interesting to see if you can find v2548, since you cannot use any 8's or 9'2 with Direct Logic.

Good luck!

Terry Woods · Aug 8, 2002

I don't know the DL-Line...

But, aren't the clock values stored in BCD?

Eric Nelson · Aug 8, 2002

Good point Bubba!!! I only looked at the problem with the instruction sequence. I should have noticed this other error!

Yes Terry, but the constant (K15) is also BCD, so it will work fine. I regularly subtract K12 from the hours value when converting to 12hr format (for HMI display purposes).

beerchug

-Eric

Terry Woods · Aug 9, 2002

Soooo...... Eric,

K15 is a constant stored in BCD Format? Says who?

I don't see K15 format being declared as BCD, but I'll take your word that it is.

So, all of the values involved are BCD.

And... K15 and V7770 are ADD'ed... Would that be a Binary ADD? or a BCD ADD?

I see Forshock ADD'ing 15-Binary (K15) to mm-BCD (V7770).

Am I totally lost, again?

bernie_carlton · Aug 9, 2002

The DL's native format is BCD. You have to specify a different instruction (eg ADDB = Add Binary) to utilize a different base. The K15 would automatically be BCD (actually Hex because you can do constants like K7A but then a BCD math instruction errors out). I get caught by the ADD instruction not allowing a constant as an argument also when I get to writing quickly.

Forshock · Aug 9, 2002

Thanks for you help guys, i will let you know if it works

Eric Nelson · Aug 10, 2002

Terry... I think Bernie answered those questions MUCH better than I would have. Still lost?

beerchug

-Eric

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Is my math right?

Forshock

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