The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
Before the tin bashing I had come to the suspicion that the drive fault that is being reported is actually the FXM-3 Field Coil current driver - clue - it's little red light was not on and should be !
But before this I thought that the best approach was to try and decode the PLC 'ladder structure' to see what inputs lead to the generated error output. There is a software package that Siemens make available called 'Step 7' intended for generating PLC code and ladders but apparently also able to read the PLC code from an existing machine.
But no - you can't just down load it - you have to jump though all sorts of hoops and sign all sorts of disclaimers before you can down load it. The Siemens web site was a nightmare today - I had to reset my password five times as it kept locking my account. Eventually I spoke to a human being in Manchester who greased the path and expedited my 1.8 Gb download. That was finished at 13:08 today, and the self installing program has JUST finished seven and a half hours later - I don't have the energy to look at it yet :bang: (But I only have a 21 day free trial !!)
So, I don't know why but I pressed the 'Spindle Jog' button on the controller, and the main spindle motor growled but didn't turn. Ah I though either the armature or the field isn't energised, but one of them is ! I rigged up my Fluke clamp ammeter and repeated the experiment on both the armature (shows 50 amps DC) and the Field coils - zilch - nowt, nothing. So that reinforces the fact the issue is quite probably the FXM-3 - this is the little card below the KTK Mentor, on which that poor 0.1 uF capacitor committed Hari Kari the other day - so this is probably collateral damage.
So off to try and source a spare tomorrow
RotarySMP:
How does a farmer get to be an experienced Mechatronic engineer? You are very good at this troubleshooting.
Mark
awemawson:
Answer: he didn’t start life as a farmer!
Qualified in Applied Physics. Employed for years running a support organisation for Process Control computers. Hobby mechanical engineering. Retired early and bought a small farm.
Easy really :lol:
PekkaNF:
I did 10 years of S5 and S7 and always needed some support manauals! No matter if the printed probram was only 150 pages of ladder/blocks or 10x that, there were plenty os stuff.
Simple I/O signal is possible to debug without commented program, but when it has plenty of internocks and sequences, it will become easily convoluted. Many alarms and interlocks are grouped toget as flags and those would be nice to have commented.
Pekka
awemawson:
Another jolly old day wandering aimlessly around the maze :bang:
I've located a service exchange FXM-3 field coil drive card and agreed a price with the vendor but the weekend has got in the way.
Firstly, the Postman brought me a parcel from the USA - a spare Baldor SMCC card. This card is a servo card that drives the tool turret. I've been having problems re-initialising the turret and a working spare would help diagnosis - EXCEPT - the card delivered is not the card I bought ! I very carefully made sure that the vendors image exactly matched my card as there are apparently several variants. This one is missing an EEPROM, has an extra LED character display, and many option sockets that are not on mine.
As I understand it, when you initialise the turret by issuing an M80 command from the Sinumerik 820T is sends a load of data to the SMCC card which effectively is it's program. You then send a tool command to it that tells it which tool position is currently presented to synchronise both systems. This data that is sent I believe to be retained in the EEPROM.
With no documentation I'm not prepared to try it and a pained email has been sent to California asking pointed questions !
The turret position is read by the system by an internal Euchner four way proximity switch block, and on one occasion I did notice that one bit wasn't being read reliably, so I reset the gap and it now reads ok.
Under certain circumstances, and I've not discovered exactly what, the Turret will initialise, and once initialised seems fine for tool changes until you power off again. I then have to thrash about trying to re-initialise.
At one point, quite repeatably it was fine if the turret had to rotate clockwise, but failed if the required tool meant an anti-clockwise rotation. This lead to what was probably a red herring, the Simodrive AC servo system that drives the X,Y, and turret servo motors - more of that later.
Here are the two variants of SMCC that I now have
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