ft232hq Future Technology Devices International Ltd., ft232hq Datasheet - Page 27

• Manufacturer Part Number: ft232hq
• Description: Ft232h Single Channel Hi- Speed Usb To Multipurpose Uart/fifo Ic
• Manufacturer: Future Technology Devices International Ltd.

Document No.: FT_000288
FT232H SINGLE CHANNEL HI-SPEED USB TO MULTIPURPOSE UART/FIFO IC
Datasheet Version 1.0
Clearance No.: FTDI #199
4.3.3 RS485 Configuration
Figure 4.3 illustrates how the FT232H can be configured as a RS485 interface.
Figure 4.3 Dual RS485 Configuration
In this case the FT232H is configured as RS485 operating at TTL levels and a level converter device (half
duplex RS485 transceiver) is used to convert the TTL level signals from the FT232H to RS485 levels. With
RS485, the transmitter is only enabled when a character is being transmitted from the UART. The TXDEN
pin on the FT232H is provided for exactly that purpose, and so the transmitter enables are wired to the
TXDEN. RS485 is a multi-drop network – i.e. many devices can communicate with each other over a
single two wire cable connection. The RS485 cable requires to be terminated at each end of the cable.
Links are provided to allow the cable to be terminated if the device is physically positioned at either end
of the cable.
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