Koyo Direct Logic 405RS D4-RSDC PLC Controller
Koyo D4-RSDC is a 24VDC serial remote I/O slave module for DirectLogic 405 (DL405) series PLC platform, developed by Koyo Electronics / AutomationDirect, used for distributed remote I/O expansion in industrial control systems. This remote I/O slave module connects to the D4-RM remote master module via RS485 twisted-pair serial bus, collecting local digital and analog I/O signals from field sensors and actuators and exchanging data with the main PLC CPU. The remote I/O slave module reduces long-distance field wiring, supports daisy-chain connection, with on-board status LED indicators for communication fault diagnosis. The remote I/O slave module serves as critical distributed control spare part for production line, water treatment and marine auxiliary control cabinet overhaul and remote I/O retrofit.

This D4-RSDC unit is rack slot mounting for DL405 base, 24VDC slave power supply, selectable baud rate 19.2k / 38.4k, maximum 7 slave modules per master, communication cable up to 1000 meters. Operating temperature 0~60°C, humidity 5%–95% non-condensing, vibration and shock resistance meets MIL STD 810C standard. D4-RSDC is legacy discontinued hardware, original production ended, only surplus and reconditioned spare stock available. Widely deployed for factory automation, pump & valve control, material handling and marine auxiliary machinery distributed PLC control.

As distributed signal extension hardware, this Koyo D4-RSDC remote slave module expands the I/O capacity of DL405 PLC and realizes decentralized field signal acquisition. Koyo DirectLogic 405 series spare parts include D4-RSDC remote I/O slave modules, D4-RM master modules, CPU units, analog I/O cards, backplanes and communication cables for PLC automation system maintenance. Koyo DirectLogic405 remote serial I/O slave modules are trusted replacement units for legacy distributed PLC control systems.