The maximum cable length depends on the data rate and cable characteristics. As a general guideline, for a data rate of 1 Mbps, the maximum cable length is around 100 meters. However, it's recommended to consult the RS-485 standard and perform signal integrity analysis to determine the maximum cable length for a specific application.
To prevent signal reflections, a termination resistor (typically 120 ohms) should be connected between the differential lines (A and B) at the end of the bus. Additionally, the termination resistor should be matched to the characteristic impedance of the cable to minimize signal reflections.
Yes, the SN75178BD can be used in a multi-point configuration. However, it's essential to ensure that only one device is transmitting at a time to prevent data corruption. A master-slave architecture or a token-passing protocol can be used to manage data transmission in a multi-point configuration.
There is no minimum number of devices that can be connected to the RS-485 bus. However, the bus should be properly terminated, and the total bus capacitance should not exceed the recommended value (typically 64 devices or 2600 pF) to ensure reliable data transmission.
Yes, the SN75178BD can operate with a supply voltage as low as 3V. However, the device's performance and output voltage swing may be affected at lower supply voltages. It's recommended to consult the datasheet and perform thorough testing to ensure the device meets the application's requirements.
SN75178BD datasheet
by Texas Instruments
