The Omron CJ1W-PRT21, also cataloged as the CJ1W-PRT21 PROFIBUS-DP I/O Link Unit, operates as a dedicated hardware component for fieldbus data exchange and distributed slave communication within SYSMAC CJ1 Series platforms.

Technical Identifier Matrix

• Brand: Omron
• Base Model: CJ1W-PRT21
• Full Part Number: CJ1W-PRT21
• Series Name: SYSMAC CJ1 Series
• Product Type: PROFIBUS-DP I/O Link Unit
• Host System: CJ1 Series PLC

Hardware Specifications

PLC Controller Processing & Backplane Communication

The CJ1W-PRT21 interface unit manages high-speed cyclic data transfer between the CJ1 backplane bus and a PROFIBUS-DP master controller. Operating across the internal backplane bus velocity framework, the unit transfers mapped I/O memory areas directly without delaying CPU instruction timing. Up to 40 units can be installed per host PLC system depending on backplane power budget constraints. Internal firmware flash compatibility ensures synchronized cyclic slave responses across the PROFIBUS-DP network segment while preventing I/O data collision or buffer overflow during high-density I/O exchange cycles.

Package Contents & Ordering Information

• 1x Omron CJ1W-PRT21 PROFIBUS-DP I/O Link Unit
• 1x CJ1 System Bus Connector Cover

Field Installation Guidelines

• Mounting: Snap the unit into the standard CJ1 CPU or expansion rack slot and lock the top and bottom slider catches onto the DIN rail.
• Wiring: Connect the PROFIBUS-DP network cable via a standard 9-pin D-sub female connector (RS-485 physical layer), securing terminal screws.
• Shielding: Terminate the PROFIBUS cable braid shield 360-deg to the metal shell of the D-sub connector to minimize high-frequency noise interference.
• Grounding: Ensure the CJ1 system functional earth (FE) terminal is bonded directly to the main panel ground bus using a low-impedance copper strap.

Frequently Asked Questions

• What is the maximum current drawn by the CJ1W-PRT21 from the backplane?

  The module draws a maximum current of 400 mA at 5 VDC directly from the PLC backplane power supply rail.

• How is the PROFIBUS-DP node address set on the CJ1W-PRT21?

  The node address is selected in the range of 00 to 99 using two physical rotary switches located on the front panel.

• How many CJ1W-PRT21 units can be installed in a single CJ1 PLC system?

  A maximum of 40 units can be installed per host PLC system, subject to total backplane power supply current limits.

• What physical envelope dimensions apply to the CJ1W-PRT21 module?

  The module physical dimensions measure 3.1 cm x 9.0 cm x 6.5 cm with a net unit weight of 0.09 kg.

• Does the CJ1W-PRT21 operate as a PROFIBUS-DP Master or Slave?

  The CJ1W-PRT21 functions specifically as a PROFIBUS-DP Slave I/O link unit for cyclic data exchange with a DP master.

• What are the operating ambient environmental limits for this unit?

  The module operates in ambient temperatures from 0 deg C to +55 deg C and relative humidity from 10 % to 90 % (non-condensing).

• What physical communication interface does the CJ1W-PRT21 use for network connection?

  The module utilizes a standard 9-pin D-sub RS-485 connector interface for PROFIBUS-DP network wiring.

• Does the CJ1W-PRT21 require external 24 VDC field power for communication?

  No, the unit operates entirely on internal 5 VDC backplane power supplied by the host CJ1 power supply module.