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A Hub for RS-422 and RS-485 Devices
Wire Your Bus Like a Star
RS-485 or RS-422 buses are still widely used in industry for access control, video surveillance and many other applications. However, the standard requires daisy-chain wiring, which can be restrictive. Here’s how to adapt to star topology wiring.
Component list
Component List
Resistors (0805, 0.1 W)
R1, R2, R7…R9, R31, R37…R40 = 4.7 kΩ, 1%
R3, R41…R45 = 1 kΩ, 1%
R4, R10 = 22 kΩ, 1%
R5, R6, R13, R20, R25, R30, R32 = 120 Ω, 1%
R11, R12, R14…R19, R21…R24, R26…R29, R33…R36 = 47 Ω, 1%
R46…R55 = 560 Ω, 1%
Capacitors
C1 = 47 µF 35V
C2 = 220 µF 10V
C3…C5, C8, C12…C14, C24, C30 = 100 nF, 0805
C6, C7 = 1 nF, 0805
C20 = 10 nF, 0805
Inductors
L1 = 100 µH
Semiconductors
D1, D2, D4…D6, D28 = PML4148
D3 = 1N4004
D7 = MBRS130LT3
D8…D27 = PESD5V2S2UT
IC1, IC2 = 74HC14D
IC3, IC6…IC9 = MAX489CSD
LED1, LED3…LED8 = 5 mm green LED
LED2 = 5 mm orange LED
U1 = LM2674-5
Miscellaneous
JP1…JP5 = 2-pin male header, 2.54 mm pitch
X1, X7 = 2-pin connector, 5.08 mm pitch, MSTBVA 2,5/2-G-5,08
X2…X6 = 5-pin connector, 3.81 mm pitch
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