word subtract

[Guest anti-guest]

I have a big problem!!!! I'm on probation and i need to conclued a exercise based on timers and counters. My problem is that i need to subtract three consecutive words with other three consecutive words, (s,s+1,s+2) - (s1,s1+1,s1+2) and the result should be placed in d,d+1,d+2. The plc that i'm using is Cj1h-h from Omron, and the software is the cx-programmer 3.0, can anyone helpme???

[Jay Anthony 118]

I tried a few values and they seemed to work. Try this out:

[Guest Gili]

Sorry but I have to add something. You have to start with CLC before the first subtract. If you don't then if the CARRY was ON before this calculation, the answer will be smaller by "1" then the correct answer. CLC-carry reset -BCDL(417) - subtract the lower portion and if needed set carry to 1 (borrow) -BCD (416) - subtract the higher portion with the present carry position - if answer is negative carry is set. maybe you want to use in here Gili

[Jay Anthony 118]

If you give students the whole answer, what do they learn?

[Guest anti-guest]

Thanks, now i understand the bcd instruction.