Happy Thoughts, Happy Life
1
Coinco Multi-Drop Bus (MDB) Virtual Test Box VMTB-400
Coinco Multi-Drop Bus (MDB) Virtual Test Box VMTB-400
DATE: 2010/04/20::
2
EzLink Vending Machine
EzLink Vending Machine
DATE: 2010/03/28::
3
WS2812b Led pixel wall with bespoke 18F26K22 processor and pc interface
WS2812b Led pixel wall with bespoke 18F26K22 processor and pc interface
DATE: 2014/06/11::
4
Ezlink Vending Machine
Ezlink Vending Machine
DATE: 2010/03/29::
5
Mars VN4510 4 tube mdb coin mech changer vending machine repair
Mars VN4510 4 tube mdb coin mech changer vending machine repair
DATE: 2014/12/10::
6
Ezlink vending machine
Ezlink vending machine
DATE: 2010/04/01::
7
Datalogic automation training setting configure ds2100 ds4800 matrix200 matrix410 barcode scanner
Datalogic automation training setting configure ds2100 ds4800 matrix200 matrix410 barcode scanner
DATE: 2012/02/11::
8
Hacking an Invacare Pronto Electric Wheelchair - Part 9 (newly discovered footage from 2010)
Hacking an Invacare Pronto Electric Wheelchair - Part 9 (newly discovered footage from 2010)
DATE: 2014/10/21::
9
POLIN MULTIDROP JUNIOR
POLIN MULTIDROP JUNIOR
DATE: 2011/01/12::
10
Molex Multi-Drop Sealed Connector System
Molex Multi-Drop Sealed Connector System
DATE: 2011/02/28::
11
MULTIDROP JUNIOR
MULTIDROP JUNIOR
DATE: 2012/04/17::
12
Multidrop Classic Polin cz. 1/2 - www.vissail.pl
Multidrop Classic Polin cz. 1/2 - www.vissail.pl
DATE: 2010/11/20::
13
Bus (computing)
Bus (computing)
DATE: 2014/08/24::
14
ProBAKE Bakery Equipment - POLIN MULTIDROP COMPACT Depositor
ProBAKE Bakery Equipment - POLIN MULTIDROP COMPACT Depositor
DATE: 2012/05/29::
15
Multi Drop Route Planner - Integrated Skills
Multi Drop Route Planner - Integrated Skills
DATE: 2014/07/07::
16
FOULHOUX BAKERY & FOOD EQUIPMENT INC MULTIDROP TWINY
FOULHOUX BAKERY & FOOD EQUIPMENT INC MULTIDROP TWINY
DATE: 2009/09/13::
17
Multidrop applications example for Mathews Engineering FETAMP1
Multidrop applications example for Mathews Engineering FETAMP1
DATE: 2011/03/26::
18
Polin Multidrop MD 393 Tipo "C" II
Polin Multidrop MD 393 Tipo "C" II
DATE: 2011/11/10::
19
BID ON EQUIPMENT: Listing 178800 - POLIN 46MTRFL Multidrop Depositor With Wire-Cut Attachment
BID ON EQUIPMENT: Listing 178800 - POLIN 46MTRFL Multidrop Depositor With Wire-Cut Attachment
DATE: 2014/01/22::
20
BakeryMachinery.Net Mimac Multi Drop Cookie Machine.mp4
BakeryMachinery.Net Mimac Multi Drop Cookie Machine.mp4
DATE: 2010/09/16::
21
Bando
Bando's multi drop, VOL. 1
DATE: 2008/03/16::
22
maquina polin multidrop.3gp
maquina polin multidrop.3gp
DATE: 2012/10/01::
23
EZFILL Multi Drop Cookie Machine
EZFILL Multi Drop Cookie Machine
DATE: 2012/07/03::
24
Slow Motion 07 - Multi-drop Madness!!
Slow Motion 07 - Multi-drop Madness!!
DATE: 2010/11/24::
25
GALWAY BUSES 1996 IRELAND
GALWAY BUSES 1996 IRELAND
DATE: 2011/11/16::
26
Conversor RS232 a RS422 RS485 de Aten modelo IC-485AI distribuido por CABLEMATIC ®
Conversor RS232 a RS422 RS485 de Aten modelo IC-485AI distribuido por CABLEMATIC ®
DATE: 2013/06/21::
27
CREATE A MULTI DROP DISTRIBUTION
CREATE A MULTI DROP DISTRIBUTION
DATE: 2010/11/05::
28
Ethernet, LANs and VLANs Online Training Course
Ethernet, LANs and VLANs Online Training Course
DATE: 2013/01/11::
29
Polski Bus Nagranie z czoła autobusu
Polski Bus Nagranie z czoła autobusu
DATE: 2013/01/06::
30
Μελομακάρονο Γεμιστό
Μελομακάρονο Γεμιστό
DATE: 2012/04/17::
31
Nu Horizons - Introduction to Exar VLIO UARTS
Nu Horizons - Introduction to Exar VLIO UARTS
DATE: 2010/01/05::
32
KERALA BAKERY NEW BUS STAND PANDIKKAD
KERALA BAKERY NEW BUS STAND PANDIKKAD
DATE: 2012/06/06::
33
Sheffield 2012, England, from bus
Sheffield 2012, England, from bus
DATE: 2012/05/05::
34
Bus Coin Dispenser
Bus Coin Dispenser
DATE: 2011/02/05::
35
The bus driver needs a hat
The bus driver needs a hat
DATE: 2009/10/26::
36
What is Ethernet over RS485? (Video) FAQ 001
What is Ethernet over RS485? (Video) FAQ 001
DATE: 2013/04/26::
37
vending bus
vending bus
DATE: 2007/06/18::
38
Van Driver of the Year
Van Driver of the Year
DATE: 2013/07/19::
39
7.5T Delivery Drivers London , South East
7.5T Delivery Drivers London , South East
DATE: 2012/04/08::
40
Contoller 2 Bus Drop
Contoller 2 Bus Drop
DATE: 2014/03/29::
41
GALWAY BUSES IRELAND 2001
GALWAY BUSES IRELAND 2001
DATE: 2011/11/23::
42
No one actually seat octogenarian struggling station by bus
No one actually seat octogenarian struggling station by bus
DATE: 2012/12/29::
43
MODAR UNO (modbus arduino) part 1
MODAR UNO (modbus arduino) part 1
DATE: 2013/06/23::
44
vta ride with Marty
vta ride with Marty
DATE: 2011/03/24::
45
Serial attached SCSI
Serial attached SCSI
DATE: 2014/08/19::
46
Polleo Artyom
Polleo Artyom
DATE: 2008/09/11::
47
TinyMesh Video 6_ How to configure serial port communication in Transparent Mode
TinyMesh Video 6_ How to configure serial port communication in Transparent Mode
DATE: 2013/03/05::
48
Molex HSAutoLink™
Molex HSAutoLink™
DATE: 2012/02/21::
49
LGV 7.5 tn Cat C1 C & C+E Driver Recruitment Jobs Work Across Yorkshire & UK
LGV 7.5 tn Cat C1 C & C+E Driver Recruitment Jobs Work Across Yorkshire & UK
DATE: 2010/03/15::
50
Basic Of Communication RS232, RS422, RS485
Basic Of Communication RS232, RS422, RS485
DATE: 2014/05/19::
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From Wikipedia, the free encyclopedia
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A multidrop bus (MDB) is a computer bus in which all components are connected to the electrical circuit. A process of arbitration determines which device sends information at any point. The other devices listen for the data they are intended to receive.

Multidrop buses have the advantage of simplicity and extensibility. However, modern SDRAM chips exemplify the problem of electrical impedance discontinuity.[clarification needed] Fully Buffered DIMM is an alternative approach to connecting multiple DRAM modules to a memory controller. Since 2000, multidrop standards such as PCI and Parallel ATA are increasingly being replaced by point-to-point systems such as PCI Express and SATA.

MDB in Vending Machines[edit]

The multidrop bus used by vending machine controllers to communicate with the vending machine's components, such as a currency detector, is also called MDB (for MultiDropBus). In use since the 1980s, it is now an open standard of the National Automatic Merchandising Association, or NAMA. The devices communicate in a single-master, multiple-slave configuration using the MDB protocol, which is based on a Motorola[specify] 9-bit UART implemented as an 8-bit data value with an additional mode bit. The mode bit differentiates between ADDRESS and DATA bytes. The master sends messages containing one address byte and a variable number of data bytes. The bus "slave devices" listen for an address, and if it matches their address that slave device will process the message and respond to the master.[1] Though 9-bit compliant UARTs are not popular in PCs, they can be found in many microcontrollers.

The physical connection is realized as a serial bus with a fixed data rate of 9600 baud. There are just 2 communications signals plus the essential common-ground reference signal. The TX signal goes from the MASTER to every SLAVE device. The RX signal goes from every SLAVE device to the MASTER device. Both signals have pull-ups. The bus is driven at every transmitter by an open collector transistor driver, and isolated at each receiver with an opto-isolator - though cable harnesses carrying the communication signals may also carry 24-volt power and ground signals to devices, meaning the devices may not be isolated from each other as they share the same power bus. Some devices, however, may have alternate power supplies, especially devices with motors and high current needs such as vintage bill acceptors or currency detector devices.

MDB originated as a proprietary bus used by CoinCo for their coin-acceptors in the late 1980s and was deployed in high volume in vending machines for Coca-Cola. Coke forced CoinCo to "open-source it" in 1992 to increase competition, and NAMA released the first version of the standard in 1995, allowing other vendors to compete for the coin-acceptor portion of the vending machines (CoinCo and Mars were the 2 major suppliers in North America at the time) and also enabled alternative payment schemes (e.g. Smartcard based) to be connected to existing vending machines.

Bus addressing is based on the device type only, which allows for a very simple protocol stack, as no initial enumeration needs to be performed. But this scheme has the disadvantage that only one device of each type can be attached.

ccTalk[edit]

Main article: ccTalk

The ccTalk multidrop bus protocol uses an 8 bit TTL-level asynchronous serial protocol. It uses address randomization to allow multiple similar devices on the bus (after randomisation the devices can be distinguished by their serial number). ccTalk was developed by CoinControls, but is used by multiple vendors.

See also[edit]

References[edit]

  1. ^ "MDB Specification Version 4.2" (PDF). NAMA. 

External links[edit]

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