Instruction Set? +P Instruction? Help!

[Guest Tammy]

Hey there. I've been searching and searching and searching, but I cannot find an instruction set for the Mits A Series PLC's. I was thrown a PLC, MELSEC GPP and the code, and it's my job to decifer it. I don't have any documentation, besides the web. So far, I'm doing ok, but, what idoes the +P instruction do? I.e. -|m9036|--------|+P D1 D2| (I'm a industrial application/software developer by trade, but somehow I keep finding myself trying to wade through this stuff...) Thanks in advance!

[Guest John Smith]

As much as I have never used this instruction. And the manual is in Jinglish It seems to be a binary addition of D2 + D1 with the result stored in D2 The example given is like this D2 5678bin (b15---b0) + D1 1234bin (b15----b0) = D2 6912bin (b15---b0) Hope that helps

[Guest Tammy]

Thanks for looking it up, but i'm still really confused on how the +P instruction differs from regular decimal addittion. Using your example, 5678 + 1234 = 9612 in decimal, so I don't understand why this any different. This instruction is used a number of times in this PLC program I'm trying to figure out the nuts and bolts of (and will eventually convert to a Siemens PLC, as well...) I don't suppose anyone out there is PLC land knows if the instruction set is online anywhere?

[Guest John Smith]

The only difference from normal mitsu maths that I can see is that the result is appended in the second register rather than using a third register for the result. Normally [+ D0 D1 D2] where D0 and D1 are added and the result stored in D2

[Guest Guest]

You can also use [+ D1 D2] to accomplish the same thing, add D1 and D2 and store the result in D2. Further investigation on my part (i.e. playing with different values) has shown that the +P instruction will return 0 if the result of the addittion is <= 0. i.e [+P K1 K-2 D2] will store 0 in D2. Thanks for your help!

[navillusi 2]

Any Melsec instruction which is suffixed P (i.e. +P MOVP INCP) Will execute the instruction on the rising pulse of the logic proceeding it, i.e. a one shot instruction rather than executing it on every scan

[Guest kajal]

rajsekhar@yahoo.com

[Guest Guest]

rajsekhar@yahoo.com