Omron CJ1W-CORT21 DeviceNet Scanner Module
The Omron CJ1W-CORT21 is a DeviceNet master scanner module for the CJ-series PLC platform. It enables the CJ1/CJ2 CPU to communicate with up to 126 DeviceNet slave devices (remote I/O, drives, sensors, valves) using a single network cable.
Network Specifications
Compliant with DeviceNet specification volume 1 & 2, version 2.0. Communication rates: 125, 250, or 500 kbps (auto-detection or manual setting). Maximum network length: 500 m at 125 kbps (thick cable), 100 m at 500 kbps (thin cable). The module supports both polled and bit‑strobe I/O connections, as well as explicit messaging for parameter configuration. Number of I/O points: up to 2048 bytes each for input and output (configurable).
Hardware Features
The CJ1W-CORT21 occupies one slot in the CJ-series backplane and consumes 300 mA from the 5 V supply. It has a removable 5-pin screw terminal block (communication lines: CAN_H, CAN_L, V+, V-, shield). An integrated 5‑pin connector also provides network power (24 VDC) from the module itself (max 1 A) to supply small slaves. LEDs indicate network status (NS) and module status (MS), plus specific I/O communication errors. The module includes a DIP switch for setting node address (0–63) and baud rate.
Configuration and Programming
Configuration is done using CX-Integrator or CX-Programmer software, which allows automatic scanning of connected slaves and mapping of I/O to CPU memory areas (CIO and DM). The scanner maintains a scan list of registered slave addresses and monitors each slave's connection health. Explicit messages are sent using CMND (Command) instructions in ladder logic, following DeviceNet object model. Up to 32 simultaneous explicit message transactions can be pending.
Data Exchange and Timing
I/O refresh time depends on the number of slaves and bus load. Typical scan for 32 slaves with 16 bytes each at 500 kbps is 6–8 ms. The CJ1W-CORT21 uses a producer‑consumer model; it can also operate as a slave (Group 2 Only) when needed. The module supports automatic fragmentation for messages longer than 8 bytes. Cyclic and change-of-state production (COS) are supported for efficient use of bandwidth.
Diagnostics and Maintenance
On‑board diagnostics include: short circuit detection on the CAN bus, slave communication loss, and network power monitoring. The module stores a fault log with timestamps accessible via CX-Integrator. A reset button performs a warm restart of the network without power cycling the PLC. Replacement of the module does not require reconfiguration if the scan list is stored in the CPU memory (backup function).
Environmental and Certifications
Operating temperature: 0°C to 55°C, humidity 10–90% non-condensing. The module is UL listed (UL 508), CE marked (EN 61326-1 for EMC), and C-Tick approved. Dimensions: 31 mm wide × 90 mm high × 65 mm deep. The CJ1W-CORT21 is compatible with all CJ1, CJ1M, CJ2H, and CJ2M CPU units. For new installations, Omron recommends the CJ1W-DRM21 for higher performance, but the CORT21 remains a proven solution for existing DeviceNet networks.
