Mits 500M control - need help with ladder array thingy

[Thomas Paine]

Hey guys, first post!  Friends at Practical Machinist sent me over here b/c we were stumped.  

I have a Mitsubishi 500M control CNC machine.  There is a section of the ladders that i don't understand, and Mitsubishi couldn't help, and the OEM is defunct.  I do not have a hardcopy of the ladder circuits.

I have an output , [Y13], that i can't get to turn on because of an internal relay | M453 |       see pic 1

When i searched for relay M453, it seems as if it's in some sort of array function.  see pic 2

None of the relays from M448 thru M512 ever turn on.  I understand that all these are controlled thru this circuit, but i have no clue what is going on with the R registers, and how the heck these internal relays can be turned on.

Can you guys help explain?   Thanks!

[nehpets]

Welcome to the Forum,

The value in R2900 is minus 8431 which gives the bit pattern 1101111100010001 this is then MOV 'ed into  internal bit stores (M's).

The instruction [MOV R2900 M448 K4] moves the bit pattern generated by the value in R2900 into M448 through to M463, the K4 is the number of Nybbles (4bit groups) to mov, in this case 4 Nybbles (16 bits).

The question now is, what is actioning and putting the value into R2900?

I hope this helps

Steve

[Thomas Paine]

wow thanks man, that makes perfect sense!  

I have no clue what is acting on R2900 thru R2903.  When i search R2900, it only comes up with this line seen above.  It seems embedded in another function, i'll have to find it and report back.  

 

[Thomas Paine]

cool, you helped me figure out that the value of R2900 is equal to bit selection parameters line 1&2.

i guess i could force if i had to, but we won't go there yet.