Description
The MODICON PC-E984-685 is a programmable logic controller (PLC) CPU module from Schneider Electric’s (formerly Modicon) 984 series, designed as a compact, high-performance rack-mounted processor for industrial automation and machine control applications. It serves as the central processing unit in small to mid-sized control systems, executing ladder logic programs while managing I/O scanning, communication, and diagnostics across one or two local racks. This model features a built-in power supply and supports the full 984 instruction set, making it ideal for standalone machines, conveyor systems, packaging lines, material handling, and process control where reliability and ease of programming are paramount. With dual Modbus ports and Modbus Plus connectivity, it enables peer-to-peer networking between controllers and integration with Modbus slave devices like sensors, drives, and HMIs. The PC-E984-685 emphasizes ruggedness for factory floors, with wide input power tolerance, extensive diagnostics via LEDs, and compatibility with Modicon’s hand-held programmer for on-the-fly edits and troubleshooting.
MODICON PC-E984-685
Product Parameters
The PC-E984-685 accepts input power from 115/230 VAC 50/60 Hz (self-selecting via internal jumper, 85-132/170-265 V range) or optional 24 V DC models, delivering regulated +5 V/2 A and +15 V/0.5 A rails to the rack backplane for powering I/O modules. CPU processing leverages a 16/32-bit architecture with 512 words user memory (expandable to 2048 via memory cartridges), executing up to 985 boolean instructions per scan at 0.2-1 ms/kword typical throughput. I/O capacity supports up to 128 discrete points or 32 analog per rack (256 total across two racks), with 4 interrupt inputs (0.2 ms response) and high-speed counters (up to 10 kHz). Communication includes 2x Modbus RTU RS-485 ports (up to 19.2 kbps, 32 devices) and 1x Modbus Plus (1 Mbps token-passing network for 64 nodes/10 km multimode fiber). Rack expansion uses remote I/O drops via Modbus Plus or twisted-pair bus. Environmental ratings cover 0°C to 60°C operation, -40°C to 85°C storage, 5-95% RH non-condensing, 1 g/10-55 Hz vibration, and 15 g shock. Physical dimensions are 44.5 cm W x 30 cm H x 23.5 cm D at 4.5 kg; MTBF >200,000 hours. Diagnostics feature 8 LEDs (power, run, fault, comms, memory protect) and BCD thumbwheel for forced I/O testing.
Datasheet Overview
Datasheet specifications highlight scan times of 1 ms/base + 1 ms/1k words logic + 0.1 ms/16 I/O, with memory types including SRAM (battery-backed 4-year retention), EEPROM cartridges (8-32 kwords), and PCMCIA options. Programming uses Modicon 984 ladder logic (up to 512 rungs, 1024 words data table), with instructions for timers (0.001-3276.7 s), counters (1-32,767), skips, compares, and math (add/subtract/multiply/divide 16-bit). Interrupt handling prioritizes fast inputs over main scan. Modbus addressing supports 1-65,535 registers/coils per controller. Mechanical design fits 8-slot base (PC-E984 chassis), with cooling via integral fan (50 CFM). Power derating applies above 50°C (0.8%/°C). EMC complies with industrial Class A (FCC Part 15), safety UL/CSA 508, and CE marking. Configuration jumpers set baud rate/parity, network address (1-64), and cold/hot start modes. Fault relay (2 A/120 VAC) signals CPU errors, memory loss, or I/O faults. Expansion supports up to 7 remote drops (512 I/O total system).
MODICON PC-E984-685
Origin
Schneider Electric manufactures the MODICON PC-E984-685 series at facilities in the United States and France, rooted in Modicon’s original PLC heritage from North American production lines.
Recommended Related MODICON Models
- PC-E984-38D
Enhanced CPU with more memory and faster scan for mid-range apps. - 984-385
Rack-mount variant with integrated power supply for compact panels. - AS-B236-000
Modbus Plus network repeater, extends PC-E984-685 connectivity.
