DCI Bus
RS485 home network with a maximum of 64 terminals
Published in issue 316, December 2002
This universal bus has many applications. With a PC as a master, information can be exchanged with up to 64 slave terminals. Because each terminal contains eight selectable inputs and outputs as well as an LCD, this home network is not only suitable for use in the home, but it would also be perfect as a combined alarm/communication system for schools and small firms.Before we delve into the technical details, we will first give a brief description of the system.The backbone of the system is a complete serial bus that uses its own protocol. Data is sent to and received from a maximum of 64 terminals over long distances using an RS485 interface.The hardware of the system consists of a simple RS232 to RS485 converter and a microprocessor driven terminal. Of the latter you will obviously need to build as many as are required. The software consists of a program for the PC and one for the ‘terminal processor’.
Converter
Resistors:
R1,R3 = 470Ω
R2 = 120Ω
R4 = 100Ω
Capacitors:
C1,C2 = 100nF
C3-C8 = 10µF 50V radial
Semiconductors:
D1 = 1N4001
IC1 = MAX232
IC2 = 7805
IC3 = SN75LBC184 (or 75176)
Miscellaneous:
JP1,JP2,JP3 = 2-way pinheader w. jumper
K1 = 9-way sub-D socket (female), PCB mount, angled pins
K2 = 9-way sub-D plug (male), PCB mount, angled pins
PCB, order code 010113-1
Terminal
Resistors:
R1,R6 = 8-way SIL resistor array, 10kΩ
R2-R5 = 1kΩ
R7 = 8-way SIL resistor array, 1kΩ
R8,R9 = 470Ω
R10 = 120Ω
R11 = 100Ω
P1 = 10kΩ preset H
Capacitors:
C1 = 1µF 16V radial
C2,C5,C7,C9-C12 = 100nF
C3,C4 = 15pF
C6 = 10µF 16V
C8 = 100µF 25V
Semiconductors:
D1-D12 = LED, red, rectangular, high efficiency
D13 = 1N4001
IC1 = 4021
IC2 = AT90S8515-8PC programmed, order code 010113-41
IC3 = TL7705-ACP
IC4 = SN75LBC184 (or 75176)
IC5 = 7805
Miscellaneous:
JP1,JP2,JP3 = 2-way pinheader w. jumper
K1, K2 = 10way pinheader
K3 = 9-way sub-D plug (male), PCB mount, angled pins
K4 = 9-way sub-D socket (female), PCB mount, angled pins
K5 = 14-way boxheader
K6 = 2-way PCB terminal block, lead pitch 5mm
S1 = 8-way DIP switch
X1 = 3.6864MHz quartz crystal
LCD module: 2 x 20 characters
PCB, order code 010113-2
Disk, contains PC en controller software (incl. source code files), order code 010113-11
|
Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
|
Informative articles
Password forgotten?
)
