mdb-coin-controller

Multidrop bus (MDB) vending machine controller (VMC) for coin acceptor/changer functionality

Dependencies and execution

Prerequisites: A PC running Python 3, a coin changer (e.g. mei cashflow C7900) with MDB support and a QBIXX MDB-USB Interface.

Execution:

$ python3 MdbCoinController.py -p /dev/ttyACM0

Commands are sent according to "Section 5 - Coin Acceptor/Changer VMC/Peripheral Communication Specifications" of the MDB specification.

Init sequence

• RESET (0x08)

• POLL (0x0B), POLL, ...

• STATUS/SETUP (0x09)

• EXPANSION IDENTIFICATION (0x0F 0x00)

• EXPANSION SEND DIAG STATUS (0x0F 0x05)

• TUBE STATUS (0x0A)

• COIN TYPE (0x0C ...)

Keep-alive

TODO: use more than one command, e.g.:

• POLL

• EXPANSION SEND DIAG STATUS

RESET details

Command: RESET (0x08)

Parameters: None

POLL details

Command: POLL (0x0B)

Parameters: None

Result: needs to be interpreted on a byte-by-byte basis

Note: This is also used for keep-alive of the coin changer.

STATUS/SETUP details

Command: STATUS/SETUP (0x09)

Parameters: None

Result:

Byte	Expected Value	Meaning
Z1	0x03	Changer Feature Level = Level 3
Z2..Z3	0x1978	Country / Currency Code: Euro
Z4	0x05	Coin Scaling Factor (might on the current tube configuration)
Z5	0x02	Decimal Places (on a credit display)
Z6..Z7	0x000F = 0b1111	Indicates what coin types can be routed to the changer’s tubes.
Z8	°0x01	Coin type #0 credit: 1*Z5, i.e. 5 Euro cents (°depends on the current tube configuration)
Z9	°0x02	Coin type #1 credit: 2*Z5, i.e. 10 Euro cents
Z10	°0x04	Coin type #2 credit: 4*Z5, i.e. 20 Euro cents
Z11	°0x0A = 10d	Coin type #3 credit: 10*Z5, i.e. 50 Euro cents
Z12	°0x14 = 20d	Coin type #4 credit: 10*Z5, i.e. 1 Euro
Z13	°0x28 = 40d	Coin type #5 credit: 20*Z5, i.e. 2 Euro
Z14..Z23	0x00	Coin types #6..#15 are not used

EXPANSION IDENTIFICATION details

Result:

Byte	Expected Value	Meaning
Z1..Z3	0x4d4549	Manufacturer Code
Z4..Z15	N/A	12 byte serial number
Z16..Z27	0x4346373930304d4442202020 ="CF7900MDB"	Model #/Tuning Revision (12 bytes)
Z28..Z29	0x0127	BCD Software Version, i.e. "0.1.2.7"
Z30..Z33	0x00000007 = 0b111	Optional Features; * Alternative Payout method * Extended Diagnostic command supported * Controlled Manual Fill and Payout commands supported

EXPANSION SEND DIAG STATUS details

Result:

Byte	Expected Value	Meaning
Z1..Z2	0x0300	Current changer diagnostic information; Z1 is the main code, Z2 is the sub-code 0x0300 = OK: Changer fully operational and ready to accept coins

TUBE STATUS details

Result:

Byte	Expected Value	Meaning
Z1..Z2	0x0000	Tube Full Status (2 byte), a value of 0x0000 would mean that no coin type tube is full
Z3..Z18	N/A	Tube Status (16 bytes, one byte per coin type). Indicates the greatest number of coins that the changer “knows” definitely are present in the coin tubes.

COIN TYPE details

VMC Parameters:

Byte	Default Value	Meaning
Y1..Y2	0xFFFF	Coin Enable (2 byte), a value of 0x0000 would disable the acceptance of all coins (as on reset), a value of 0xFFFF accepts all coins
Y3..Y4	0xFFFF	Manual Dispense Enbale (2 byte) a value of 0xFFFF (default on reset) enables manual dispensing of all coin types via optional inventory switches!

Result:

tbc

DISPENSE details

Command: DISPENSE COIN (0x0D)

VMC Parameters:

Byte	Default Value	Meaning
Y1.H	0x1	High nibble (b7..b4) indicates number of coins to be dispensed (0..15)
Y1.L	N/A	Low nibble (b3..b0) indicates the coin type to be dispensed (0..15)

Response: X

Additional info: "VMCs should monitor the Changer Payout Busy response to the POLL command to determine when the entire payout cycle is completed."