Mitsubishi Newbie Question

[Mike Davidson 0]

I opened up a Mitsubishi FX2-64MR PLC and discovered the following line of code. LD M8000 MOV K4X010 K4M10 MOV K2X030 K2M26 MOV K1X004 K1M6 DMOV K8M50 K8Y000 I get that we're mapping the I/O, but what is the signifigance of the constants? (K1, K2, K4, and K8). The manuals I downloaded from Mitsubishi's website are not what I would call user friendly as far as the quirks of their programming language are concerned. I was surprised that GX-Developer does not include a Instruction list help file.

[panic mode 246]

bits can be grouped in packs of nibbles (nibble is 4-bit, two nibbles are one byte etc.). first source bit is copied into first destination bit etc. MOV K4X010 K4M10 // copy 4*4=16 bits starting from x010 to m10 (X010..X01F is copied into M10..M15) X010 -> M10 X011 -> M11 X012 -> M12 X013 -> M13 etc until X01F -> M15 the rest works the same way: MOV K2X030 K2M26 // copy 2*4=8 bits (from X030..X037 to M26..M33) MOV K1X004 K1M6 // copy 1*4=4 bits (from X004..X07 to M6...M9) DMOV K8M50 K8Y000 // copy 8*4=32 bits (from M50..M81 to Y0..Y3F) I suggest becoming familiar with User Manual for GX Developer. This is one of many things explained.

[Crossbow 295]

Check manual JY992D88101 or JY992D48301. The information you need is called 'digit designation' and is mentioned in both manuals in the section which covers the various PLC memory areas.

[Mike Davidson 0]

Thanks for the explanation, and with your directions I did find the descriptions in the Manual. Mitsubishi should really take a page from Omron concerning their manual layouts and descriptors. It looks like I am going to have to read this thing from cover to cover just to document a fairly simple program (WARNING: Sharp learning curve ahead!).

[Mike Davidson 0]

Correct me if I am reading this wrong......But if I am reading the manual right...... The FX series inputs are mapped octally so [MOV K4X010 K4M10] would map out as follows? First Nibble X010->M10 X011->M11 X012->M12 X013->M13 Second Nibble X014->M14 X015->M15 X016->M16 X017->M17 Third Nibble X020->M18 X021->M19 X022->M20 X023->M21 Fourth Nibble X024->M22 X025->M23 X026->M24 X027->M25 Sorry to keep bugging you about this but I want to make sure I've grasped the concept correctly.

[Crossbow 295]

It's not really that difficult. I learned PLCs on Omron, and was able to convert my knowledge to Modicon, Mitsubishi, Idec, and others without a huge learning curve. Everyone does things slightly differently. Every vendor has their nuances. But ladder logic is ladder logic. But your mapping is correct.