设置
快速交货
免运费
国际贸易术语
支付类型
市场产品
Configuration 3 has the RS-485 transceiver configured for half-duplex operation, which requires only two conductors for long-haul networks. Note that for long distance transmission lines the RS-485 transceiver should be set to slow-mode (115 kbps). The RS-232 receiver controls the operation mode of the RS-485 transceiver. A low at R1OUT (and hence at DI) sets the RS-485 transceiver into transmit mode by enabling the driver and disabling the receiver. A low at DI is therefore actively converted into a negative bus voltage. A high at R1OUT accomplishes the opposite and switches the RS-485 transceiver into receive mode. With the driver outputs now being high-impedance, a positive bus voltage is established by the failsafe biasing resistor network. The small deglitch circuit consisting of an inverter and a R-C-D unit prevents the occurrence of glitches on the bus during the transitions from drive into receive mode. This half-duplex level translator is the most efficient of all, as it saves an entire conductor pair versus a full-duplex level translator, and also frees up the second RS-232 channel, which can now be used for other interface purposes.
