[rags]

hello,
we bought a niigata hmc with fanuc 6m controller, we changed the old mits plc with an allenbradley plc and the machine works fine except sometimes the wrong tool comes to the spindle during tool change and we get a scare, we are running on single block now to avoid a crash .
Is this something wrong with the ladder logic which i doubt as this problem occurs only sometimes, should we look into the program syntax esp program nos/ block nos in the 6m,we are normally used to running the 0m series.

any suggestions

thanks again
rags

[Dan Fritz]

It could either be a bug in your PLCs ladder, or id could be erroneous feedback from the tool carrousel. How does the PLC know what tool you're on? Is it a rotary encoder, a set of binary limit switches, or something else? A bad encoder or a bad limit switch would fool the PLC into selecting the wrong tool even though your ladder logic is ok.

[rags]

thanks mr.fritz,
We have observed that only when the program is long and contains many subprograms this problem occurs, we are wondering if the block nos of the main program and subprogram should be unique and should never be the same which causes this problem.


We have some programs running 5 to 6 tools when we do not face this problem whereas the parts with operations on all 4 faces wherein we use many subprograms and same tool is called in a number of subprograms when we face this problem.

thanks again
rags

[ben_heinman]

I have seen somthing like this before where it was grabbing the wrong tool. What we did to fix it was buffer mask the M06. Look in your parameter manual for M code preventing buffering. It is 3411 on my control. You could also try putting an extra EOB ( after you M06 line which works pretty much the same as a G04 X.5