Separate signaling from connector shape
RS-232 is single-ended; RS-485 uses differential signaling. TTL-level UART needs its specified logic level. Record the device interface, pin labels and signal voltage requirements before deciding whether an active converter is needed.
Document the complete connection
Confirm transmit and receive assignments, reference connections and any handshake signals. For RS-485, record the device topology and termination requirements from its manual. Include isolation requirements and the power source for any converter.
Check host software with a sample
If USB conversion is involved, identify the host operating system and required driver. Agree baud rate, framing and a representative communication test. Keep a known-good wiring diagram with the verified hardware and software configuration.
Common mistakes
- Using a passive pin adapter where electrical level conversion is required.
- Assuming a DB9 connector establishes the pinout or serial standard.
What to include in your inquiry
- Device manuals and interface designation at both ends
- Pin map, logic level and handshake requirements
- Host operating system and converter power requirements
- Communication settings, topology and sample test
Use this checklist to prepare a specification. Confirm the final assembly against your equipment documentation and the agreed drawing.