CPI TALOS - Multi-Drop Bus (MDB)

Talos Operation and Service Guide
22
Multi-Drop Bus (MDB)
The Multi-Drop Bus uses a daisy chained five wire interface that includes power and bi-
directional communication between the Vending Machine Control board (VMC) and a
number of peripherals. The Bill Acceptor is one of those peripherals. Coin Mechs, debit card
readers, audit devices, etc. are examples of other peripherals. Electrically, the VMC
supplies DC power to each peripheral using two wires and communication signaling to each
peripheral using three wires.
MDB communications uses an optically isolated 9600 baud, bi-directional serial interface
with the Vending Machine Control board (VMC) as the master and the Bill Acceptor and
other as slaves. The VMC communicates to the peripherals using a half duplex polling type
protocol. Each peripheral (up to 32) is assigned a unique address, defined commands, and
defined response data. During operation, the VMC polls each of the peripherals and
interrogates that peripheral with various commands to further control it.
Note: MDB is supported only on 24 VAC/MDB models.
Connections
Pin Name (all pins refer to P1)
Type
24 VAC/MDB
pin
MDB NEGATIVE (-)
Power
16
MDB POSITIVE (+)
Power
23
MDB COMMON
Bus
Ground
28
MDB MASTER TX
Input
14
MDB MASTER RECEIVE
Output
6
OUT-OF-SERVICE POWER (200 ohms to +5VDC)
Output
25
OUT-OF-SERVICE_NOT
Output
22