Part Details for DS485TMX/NOPB by National Semiconductor Corporation

The maximum cable length for reliable data transmission depends on the baud rate, cable quality, and noise environment. As a general guideline, the DS485TMX/NOPB can support cable lengths up to 4000 feet (1219 meters) at lower baud rates (e.g., 9600 bps) and shorter lengths (e.g., 1000 feet or 305 meters) at higher baud rates (e.g., 115200 bps).

To ensure reliable data transmission in noisy environments, use twisted-pair cables, keep the cable length as short as possible, use shielded cables, and implement error-checking mechanisms such as CRC or checksum in your protocol. Additionally, consider using a common-mode choke or ferrite beads to filter out electromagnetic interference (EMI).

The DS485TMX/NOPB can support up to 32 devices on a single bus, but the actual number of devices that can be connected depends on the bus loading, cable length, and noise environment. It's recommended to limit the number of devices to 16 or fewer to ensure reliable operation.

To handle bus contention and collisions, implement a collision detection and arbitration mechanism in your protocol. This can include techniques such as CSMA/CD (Carrier Sense Multiple Access with Collision Detection) or token-passing. Additionally, consider using a dedicated bus controller or master device to manage bus access and prevent collisions.

The power consumption of the DS485TMX/NOPB depends on the operating mode and supply voltage. In normal operation, the device typically consumes around 10-15 mA from a 5V supply. In shutdown mode, the current consumption is typically less than 1 μA.