Configured for DeviceNet industrial network interfacing and multi-node message routing in CJ/NJ Series architectures, the Omron CJ1W-DRM21 (CJ1W-DRM21 DeviceNet Unit) provides direct physical/electrical execution across trunk and branch transmission topologies.

Technical Identifier Matrix

• Base Hardware Model: CJ1W-DRM21
• Full Part Number: CJ1W-DRM21
• Product Type: DeviceNet Communication Unit
• Series Family: Omron SYSMAC CJ Series
• Unit Classification: CPU Bus Unit
• Supported Controller Families: CJ Series, NJ Series
• Maximum Node Capacity: 64 nodes (Masters, Slaves, and Configurator)

Hardware Specifications

Omron Backplane Bus Velocity & Real-Time Logic Execution

The CJ1W-DRM21 operates as a CJ-series CPU Bus Unit, interfacing directly across the high-velocity backplane bus to exchange cyclic I/O data and explicit message frames with maximum processing efficiency. Firmware flash memory routines manage protocol mapping into the CPU memory space, enabling deterministic communication synchronization without degrading ladder scan performance or increasing backplane transfer latency.

Package Contents & Ordering Information

• 1x Omron CJ1W-DRM21 DeviceNet Unit
• 1x DeviceNet 5-pin open style terminal block connector
• 1x Hardware instruction sheet

Field Installation Guidelines

• Rack Mounting: Align the unit backplane connector with the designated slot on the CJ/NJ CPU or expansion rack and press until the locking levers engage firmly.
• Network Wiring: Wire the DeviceNet trunk and branch lines using approved 5-wire shielded cables, attaching signal lines V+, CAN_H, Drain, CAN_L, and V- to the terminal block connector.
• Cable Shielding: Terminate the cable drain wire directly to system ground at a single power supply point, maintaining continuous 360-deg braid shielding across the network.
• Chassis Grounding: Connect the CPU rack functional earth (FE) terminal to the panel grounding bus using a dedicated conductor with an electrical resistance under 100 Ohms.

Frequently Asked Questions

• Is hot-swapping supported for the CJ1W-DRM21 on a live CJ/NJ backplane bus?

  No. Internal system power must be disconnected prior to inserting or removing the unit to prevent hardware logic damage.

• What current does the CJ1W-DRM21 draw from the internal backplane power supply?

  The unit draws a maximum current of 290 mA at 5 VDC from the internal CPU rack backplane bus supply rail.

• What is the external voltage and current requirement for the DeviceNet interface?

  The DeviceNet physical transceiver operates on 11 to 25 VDC supplied externally, drawing 18 mA maximum.

• What selectable transmission speeds are available on the DeviceNet network?

  Baud rates are selectable via DIP switches at 500 Kbps, 250 Kbps, or 125 Kbps based on network distance.

• What is the maximum node capacity supported by a single CJ1W-DRM21 network line?

  The unit supports up to 64 addressable nodes, which includes Masters, Slaves, and network Configurators.

• What maximum message frame length is supported for explicit messaging?

  Explicit message communications support a maximum frame length of up to 542 bytes per transmission packet.

• How are terminal resistors installed on a DeviceNet network segment?

  Install 121-Ohm, 1/4-Watt terminating resistors across the CAN_H and CAN_L signal lines at both physical ends of the trunk line.

• What grounding resistance limit is required for the controller rack installation?

  The central panel protective earth grounding connection path must maintain an electrical resistance strictly under 100 Ohms.