RS232 - RS485 Converter with Automatic RX/TX Control

Konusu 'Elektronik Devreler' forumundadır ve guclusat tarafından 26 Mart 2012 başlatılmıştır.

  1. guclusat

    guclusat Tanınmış Üye Süper Moderatör

    14 Haziran 2009
    Ödül Puanları:
    [h=2]Project Description[/h] RS232 is one of the most used, easy to develop and easy to apply communication protocol. We generally encounter to this standard at the MCU applications. But it has some restrictions. It allows us to use maximum 15 meters cable. Good wiring, low baud rates and less noisy mediums may allow us to exceed this limit a little more. The main problem here , when the distance increases, the noise at the common ground line also increases. Another issue, RS232 allows only two devices to communicate reciprocally. More than two devices can not communicate at this line and we need another solution for this situation.
    RS485 is the standard that solves this problems. The main difference is, RS485 transfers the data depending on the potential difference between the two communication wires. The polarity defines the logic state of the signal. You can transfer data up to 1220 meters far away and with a rate up to 10 Mbs. 32 devices can join the RS485 network.
    While transferring the data, MAX232 converts the signal coming from the DB9 connector to TTL/CMOS level. Then MAX485 transfers the input signal coming from the MAX232 to the RS485 line as a voltage difference. While receiving the data, MAX485 detects the data at the RS485 line and transfers it to MAX232 then output can be taken from the DB9 connector.
    Converter controls the “Receive” and “Transmit” modes automatically.
    R1, R2 : 1K 1/4W Resistor
    R3, R4, R5, R11 : 2.2K 1/4W Resistor
    R6, R7 : 560 Ohm 1/4W Resistor
    R8, R9 : 47 Ohm 1/4W Resistor
    R10 : 120 Ohm Resistor
    C1 : 10uF 50V Electrolytic Capacitor
    C2, C4 : 100n Polyester Capacitor
    C3 : 10uF 16V Electrolytic Capacitor
    C5, C6, C7, C8 : 1uF 16V Electrolytic Capacitor
    D1 : 1N4007 Diode
    L1, L2 : Red and Green LEDs
    Q1 : BC327 PNP Transistor
    U1 : MAX232N
    U2 : MAX485CPA
    U3 : LM7805
    J1 : DB9 PC Mount Female Connector
    U4, U5 : 2 Terminal PCB Terminal Block


    Ekli Dosyalar:

Benzer Konular - RS232 RS485 Converter
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