The Omron CJ1W-DA021, also cataloged as the CJ1W-DA021 Analog Output Unit, operates as a dedicated hardware component for digital-to-analog signal conversion and process control variable generation within CJ Series PLC backplanes.

Product Designation & Architecture Analysis

The Omron CJ1W-DA021 occupies a single slot on CJ1G, CJ1M, CJ2M, or CJ2H CPU bus racks. Its standardized model structure highlights specific operational capabilities:

• CJ1W: Dedicated I/O module system platform for Omron CJ Series programmable controllers.
• DA: Digital-to-Analog hardware architecture designed for field voltage and current loops.
• 021: Functional designator indicating 2 analog output channels with a 1/4,000 resolution profile.
• Electrical Bus Interface: Photocoupler isolation separates internal PLC controller signals from field wiring side circuitry.

Operational Hardware Specifications

Backplane Synchronization & I/O Density Scaling

The module streams converted analog variables over the high-speed local backplane bus without requiring additional CPU polling cycles. Internal bus communication velocity guarantees rapid data write commands directly from allocated memory words to the digital-to-analog converter. Scaling algorithms adjust firmware register values in real time to sustain deterministic loop output states under dynamic processing loads.

Standard Module Package Contents

• 1 x Omron CJ1W-DA021 Analog Output Unit
• 1 x 18-point detachable terminal block with M3 screw terminals
• 1 x Hardware mounting instruction manual

Field Termination & Wiring Practices

• Terminal Screw Torque: Tighten all M3 terminal block screws to a torque rating of 0.5 N m to ensure secure connection without stripping threads.
• External Power Wiring: Wire an independent, regulated 24 VDC external power supply to the terminal block to supply output driver circuits.
• Shielding Protocol: Use twisted-pair shielded cables for all analog voltage and current loops. Ground the shield at the module panel earth side only.
• Signal Separation: Keep analog signal cables separated from AC power lines and high-frequency inverter outputs by a minimum distance of 300 mm.

Frequently Asked Questions

• What causes the output voltage or current to freeze when the CPU enters STOP mode?

  The module's hold function is configured to maintain the last valid converted value. Change the memory setting to CLEAR if zero output is required during CPU stop.

• Can channel 1 operate in 4-20 mA mode while channel 2 operates in -10 to 10 V mode?

  Yes. Each analog channel is individually configured in system memory for specific voltage or current signal ranges.

• Is channel-to-channel isolation supported on the CJ1W-DA021 terminal block?

  No. Photocoupler isolation exists between field circuits and the backplane logic, but there is no electrical isolation between individual output channels.

• How is external 24 VDC power connected to the unit?

  External 24 VDC power must be wired directly to the designated terminals on the 18-point detachable terminal block to power the internal output stage.

• Does the CJ1W-DA021 support hot-swapping while the rack is powered?

  No. Removing or inserting the unit while the CJ Series backplane is energized can damage module electronics and fault the controller.

• What is the response time for both analog output channels to update?

  The total D/A conversion cycle time is 1.0 ms per point, resulting in a total update period of 2.0 ms for both active output points.

• What load resistance limits apply when using the 4-20 mA current output range?

  The connected load impedance must not exceed 600 ohms per current output channel to maintain calibrated signal accuracy.

• What happens if the external 24 VDC power supply drops below operating limits?

  The module stops outputting current/voltage signals, flags a power supply alarm in the PLC status words, and forces outputs to 0 V or 0 mA.