Aims

• redo all internal wiring and logic, except the refrigeration parts
• make the machine more safe by doing things properly and reducing the voltage of exposed components
• keep the software interface as simple or more simple than before
• make the buttons on the front of the machine work for dispense
• make it extensible so things can be added on
• give the machine a general service where necessary (seals, rust protection, oil)

Draft Bill of Materials

• http://www.frozencpu.com/cat/l3/g36/c265/s668/list/p1/Fans-AC_115V_Fans-120mm_AC_Fans-Page1.html

• http://au.element14.com/honeywell-s-c/v7-5f17d8/micro-switch-pin-plunger-spdt-3a/dp/1796593 (low force microswitches for empty detection)

• http://au.element14.com/omron-electronic-components/vx5-1a2/microswitch-v3-plunger/dp/673626 (alternative)

• http://au.element14.com/cherry/kwgb-qaca/micro-switch-button-spdt-5a-250v/dp/4549259 (50gf, may be too high)

• http://www.ozautoelectrics.com/trailer-cable-5-core-6m-roll.html (5 core wire for actuators)

• http://www.ebay.com.au/itm/5-Core-Cable-Wiring-Wire-Trailer-Parts-Lights-per-Meter-/110609219198

• http://www.ebay.com.au/itm/0-5mm-9-Core-Irrigation-Cable-per-metre-/300341913942 (for front switches and LED's)

Internal PLC IO Requirements

• 10x24V DC input for can sensing (would it be worth multiplexing this?)
• 7x24V DC input for front door buttons (ditto with the multiplexing question)
• 1x24V DC input for manual dispense mode button
• 10x?110V? relay outputs (this assumes linear actuators return by themselves)
• 7x DC outputs for empty slot display

Process

• empty the machine and bring it into the clubroom. This means everything won't have to be packed up at the end of the day while we're working on it
• remove one of the stacks and test a slot actuator to see what it runs off. This determines what hardware we use to drive everything, so we need to know.
• purchase all required hardware (PLC, wiring, connectors, switches, etc.)

• write software (state machine based programming implemented in ladder logic, should be quite trivial)

• wire up on the bench and test
• service the machine. A can of zinc spraypaint wouldn't go astray on some of the rust spots I think. Check all the seals. Oil what needs oiling. Clean what needs cleaning.
• install everything into the machine and test

Measured things

• Can drop process: 400ms on, 500ms off, 660ms on, 300VAC peak-to-peak, 1.8A
• Wire lengths:
  • Actuator units 0,1,2,3: 80cm actuator to wire harness, 210cm harness to corner of machine door, 40cm up door, 45cm across, 40cm up to terminal block (4-core minimum)
  • Actuator units 4,5: 80cm actuator to wire harness, 170cm harness to corner of machine door, 40cm up door, 45cm across, 40cm up to terminal block (4-core minimum)
  • Actuator units 6,7,8,9: 80cm actuator to wire harness, 140cm harness to corner of machine door, 40cm up door, 45cm across, 40cm up to terminal block (4-core minimum)
  • Buttons: 75cm across front of door, 60cm down edge of door, 45cm across, 40cm up to terminal block (8-core minimum)
  • Lights: 75cm across front of door, 60cm down edge of door, 45cm across, 40cm up to terminal block (8-core minimum)