The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
Thanks for the link Ade, no I don't have that particular manual. It's for the S5-135U Stand Alone PLC that the PLC embedded in the 820T controller emulates.
Assuming here, but I suppose that Siemens decided rather than have a physically separate PLC they could time slice the CPU in the controller to do the same job logically. The PLC even reports itself as a 135 when I connect to it.
I've yet to get fully to grips with it, but as I understand it the PLC copies it's field of input and output data to the CNC controller and vice versa once every pass of the program and that is how they communicate, setting the flag bits.
. . . It's a whole new world in there ! Bring back COBOL or ALGOL I say or even FORTRAN but I was happy with Z80 assembler :clap:
PK:
So I've spent a little time studiously ignoring Andrews 'How's it going' messages whilst staring at that probe trying to figure out how to get into it.... It resisted hand opening, and there seemed no way to grip it with tools without digging into the anodised finish. I'm certain that special wrench #27 exists and does the job perfectly. But I aint got one! I don't even have a 25mm collet to grip the shank..... So it sat on the healing bench for a few days whilst we stared at it.. In the end some disassembly allowed me to bolt on a strip of metal that I could get a spanner onto, and a bit of scrap bored to 25, slit, and held in a vice did the job.
And we're in!..
We can now trace signal from the transmitter through to the receiver and make sure it's waking up...
We've flashed some IR at the transmitter and seen signal come out of it's photodiode, so it looks like that bits OK now....
RotarySMP:
Hello Andrew,
Thanks for posting in this manor, as your documentation of your systematic approach to trouble shooting is a good lesson in how to solve this kind of problem.
Is there a point where you cut your losses, dump the original controller/PLC and retrofit to LinuxCNC? I'd appreciate hearing your thoughts on that.
On my MAHO 400E I didn't go very far down the path of fixing the existing Phillip's 432 installation, as the functionality of a 2.5D controller with 16kb ram didn't seem worth it, when compared to the significant improvement in capablity with LinuxCNC (full 3D, unlimited program length and look ahead). On a lathe I guess that equation balances out differently.
Mark
awemawson:
PK good progress, thank you :thumbup:
But I'm a little confused - are you saying that the OMM is now responding both ways, or the probe module ?
awemawson:
Mark,
99.9% of the PLC is working fine and is rather good, so absolutely no way it'll be changed.
I've spent a couple of days pouring over all the documentation that I have, and suitably cross referencing the innards of the PLC program - I'm up to just short of 300 references in the list so far :bugeye:
However I am closing in on the M20 issue, having identified the bits of the program that are activated by M20 - it's an uphill struggle but progress IS being made.
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