The maximum cable length supported by the ST485CDR is dependent on the baud rate and the type of cable used. As a general rule, the maximum cable length is around 1200 meters at 9600 bps, but it can be shorter at higher baud rates.
To ensure reliable data transmission with the ST485CDR, it is recommended to use a balanced transmission line, such as a twisted pair cable, and to follow proper termination and grounding techniques. Additionally, using a common mode choke and a shielded cable can help to reduce electromagnetic interference (EMI).
The ST485CDR and the SN65HVD72 are both RS-485 transceivers, but they have some differences. The ST485CDR has a higher data rate (up to 50 Mbps) and a lower power consumption (down to 1.8V) compared to the SN65HVD72. The ST485CDR also has a built-in 15kΩ pull-up resistor on the receiver input, whereas the SN65HVD72 does not.
To handle hot swapping with the ST485CDR, it is recommended to use a bus holder circuit to maintain the bus in a defined state during power-up and power-down. This can be achieved using a voltage supervisor and a power-on reset circuit.
The maximum number of nodes supported by the ST485CDR is 32, as per the RS-485 standard. However, the actual number of nodes that can be supported may be limited by the specific application and the cable length.
ST485CDR datasheet
by STMicroelectronics
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