What it is and what it does
The TM171ALAN is a LAN-to-RS485 bridge in the Modicon M171/M172 range — takes a 24 V AC/DC supply (1 W) and gives you three screw terminals for RS485 and three for the LAN side. Same part, different passport: this is the active, current-production SKU, so no last-time buy scramble. Houses in an IP20 enclosure that fits a 35 mm DIN rail (1.4 in wide, 2.4 in deep, 4.3 in tall). Overvoltage category I and pollution degree 2 — typical for dry indoor control cabinets.
Compliance and documentation
Certified to IEC 60730-1, IEC 60730-2-9, and UL 60730-1. That covers the safety standard for automatic electrical controls — enough for most North American and European panel builds. Storage range -30 to 85 °C, operating -10 to 55 °C, 5–95% RH non-condensing.