Denford Mirac communications problem

[mark35gun]

first of all let me say hello to everyone i am new to the forum so i will apologise for any mistakes in advance
i have a lcb3 mirac with the keyboard and monitor built in
the problem that i am having is-"machine communications error you must restart the machine".
this appears to happen at any time,in fact appears to be quite at random
when it happens none of the control buttons work with the exception of the estop, its quite alarming when traversing into the job and it keeps going when you take your finger off the button.
could anyone help? i really have not got a clue where to start to try to solve this problem, any help/advice would be very much appreciated
thankyou in advance

[Denford Admin]

I don't know anything about these vintage machines, but would guess that there is communication data corruption - possibly due to noise, poor earth connections or broken wires. eg, it manages to send the command to jog the machine, but the command to stop jogging gets corrupted and therefore not actioned (maybe the fact the motors/drives are active, causes more problems with noise?)
I'd certainly start with a good visual check of the wiring and connectors...

[mark35gun]

thanks for the reply i have checked all that you mention , it will also throw up this error when the m/c is stationary,however it will almost certainly do it if the auto toolpost doesnt index properly,likewise it will throw the same error if for example, you stall the spindle either turning or drilling.
so it would seem that the message is a generic one ,i.e it throws an error when it gets a signal,or doesnt get one when it should? anyone got any comments?
also does anyone have any spare parts for the machine i.e the computer side of it,rs 232 card ect ect?
finally i know that i should put on details of my m/c however the id plate on the side,the details were wrote on ,probably in permanent marker.....
and are now illegible so any details i get in the future i will update my profile
best regards to all.

[Denford Admin]

Could be worth getting a multimeter and checking the voltages aren't a bit out - especially the 5 volts on the control board.
Hopefully someone else has more idea what the message is actually triggered by - I'm just shooting in the dark

[mark35gun]

right then, after some messing about with the m/c if you programme a simple turning programme i.e an ever decreasing diameter to a set size with varying speeds and feeds all appears to be ok (touch wood)
if however you programme a threading cycle(G73 multipass threading) then the mc will do one pass only, when z rapids back to the start position it will throw the error message every single time. i have tried different speeds,pitches,start point,end point, in fact i have tried everything i can think of to no avail it does it every single time i try it?????????
one thing of interest, the z axis motor makes a whining noise when in a threading cycle not apparent when feeding or rapiding its not that it sounds bad just different. i must say that i am becoming suspicious of the z axis motor. needless to say i am not a happy man

[Martin]

Hi there.
It sounds more like a PC fault. it may be worh removing some of the cards in the PC & cleaning the contacts before re-inserting.There is no feedback from the X & Z axis motors so it`s unlikely for that to be causing the comms error. It`s exactly what it say`s. A communication problem between the LCB3 Board & the PC.

[Denford Admin]

The Z motor may sound funny when threading because its following the speed of the spindle - which will probably be fluctuating as the thread cuts.

If this error only occurs while threading, maybe there is something wrong with the program which is causing the system to get confused ie,crash ?

Hopefully someone else can advise on any threading issues there were with this control...

[mark35gun]

thanks gentlemen i will check the connections between lcb3 board and the pc hope you are right! i will post my findings
best regards
mark.