RS-485 is an electrical interface, not a command language
Why matching the two wires does not establish device-level compatibility.
Separate the layers
RS-485 specifies electrical characteristics for drivers and receivers. It does not define an application command set, device addresses, or a connector pinout. Two products can both advertise RS-485 while using incompatible message formats. TI’s introductory material makes this distinction explicit.
Collect the complete interface description
For each device, record the connector pinout, signal polarity definitions, serial settings, application protocol, addressing, and response timing. Use the manufacturer’s signal definitions rather than assuming that A and B labels are consistent between products. Keep a known-good command and its expected response with the commissioning record.
Review the physical bus
TI recommends cable termination at the bus ends for appropriately terminated RS-485 networks. Biasing and receiver fail-safe behavior are separate design considerations. Check the actual topology, cable, transceiver characteristics, data rate, and existing termination before adding components. A bench connection with a short cable does not validate a longer installed network.
Test one device first
Begin with one controller and one device. Confirm the documented application exchange, then add nodes gradually. Record both transmitted and received bytes. This order helps distinguish wiring and timing faults from an incorrect register map or command parser.
Primary references
Read these alongside the exact device documentation. The workflow above is an editorial synthesis, not a report of a completed hardware test.