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| The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20) |
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| awemawson:
I admit to a nice inner glow and a not inconsiderably swollen head after today's achievements :ddb: :ddb: Wanting to add a 'Wash Down' facility - ie a simple hose gun off the coolant pump to manually wash chips away and clean up a work piece, I decided that I needed a pair of valves acting in anti-phase. One in line from the coolant pump to the Tool Turret, and a second one from the coolant pump to the gun of the wash down facility. Dead easy with relays and buttons, but I thought, why the heck should I be adding MORE buttons when the 820T is crawling with ones that have never been implemented, and there's a perfectly good PLC program running that I aught to be able to modify. Having identified the input addresses of the front panel buttons that I wanted to use (I96.3 and I96.4) and found two spare 24 volt digital outputs (Q2.6 and Q2.7), with a bit of trepidation I started poking about in the PLC program live on the machine. Now despite months of work learning about the PLC, it's 'STEP5' programming language, managing to down load and produce a paper copy of the PLC 'ladder logic', I have only before passively read what is in it and never attempted to edit, alter or add it it. So this is a first. STEP5 is a very frustrating program to use to program, however today I've managed to add another 'Rung' to the ladder (Segment 173 to be pedantic!) and amazingly it works :ddb: :ddb: Trivial in the extreme as far as the logic is concerned. One button sets an S/R flip flop, the other button resets it, and it's output controls one of the valves. Now I need to add subtleties to it, interlocking so it will only work when the door is open, will not work when the chuck is spinning or a program is running, and ensuring that when one valve opens the other closes, but that's finessing that can be done at my leisure, the point is I've proved that it's possible and I've managed to do it - hence the warm glow. . . . back to reality - I need to go muck out and feed the pigs ! |
| PekkaNF:
ommmmmmmMMMMMMM - gggggGLOW! You can go down to nearest town with zipper open carrying a poster: I KNOW HOW TO PROGRAM S5 AND MAKE CHILDREN! :D Pekka |
| tom osselton:
Nice to see you can add to it, my mill just has a manual valve on the front of it I have to turn. I haven’t had a swollen head since that frying pan incident! :wack: |
| awemawson:
Thanks Chaps! I've been looking for suitable 17.5 mm pipe clamps to hold the extra pipes when the 'wash down' goes in. Couldn't find any so I printed some on the Cetus 3D printer in ABS at 99% fill |
| awemawson:
Still not having the solenoid valves to hand to complete the 'wash down' facility I decided to finish off the alterations to the PLC ladder to prevent wash down when the spindle was turning, or the door open - fairly obviously you can ONLY wash down with the door open and don't want the pump diverted to the gun (which will hang on the door probably) with the door closed. Again absolutely trivial code, but I discovered an interesting and useful STEP5 quirk while doing it. You can display the ladder diagram rung by rung, and set it to display the status of each node in real time. So in the following picture of segment 173, the door interlock node is displayed in GREEN as the door is shut and it's contact active - quite handy for fault finding I think. So two rungs added: Segment 173 is an R/S flip flop set and reset by the appropriate panel buttons, but inhibited by a closed door or a running spindle, and is reset by the general 'Reset' button on the machine. If the flip flop (= Flag 140.2) is set, Q 2.6 drives the 'wash down' solenoid. Segment 174 merely takes the flag 140.2 and if it is NOT set activates Q 2.7 which drives the solenoid valve directing coolant to the turret and it's mounted tooling. . . .seems to work so far . . . :scratch: |
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