What to do if Omron SYSMAC CJ1W-EIP21 shows a Duplicate unit number?
- TTrevor BentonSep 9, 2025
If the same unit number is set on another Unit, set the unit numbers correctly and restart the EtherNet/IP Unit or built-in EtherNet/IP port.

What to do if Omron SYSMAC CJ1W-EIP21 shows a Duplicate unit number?
If the same unit number is set on another Unit, set the unit numbers correctly and restart the EtherNet/IP Unit or built-in EtherNet/IP port.
Why does Omron Network Hardware show a CPU Unit event servicing timeout, and how to fix it?
If a timeout occurred during an operation such as reading the routing tables to the CPU Unit, replace the EtherNet/IP Unit or (for a built-in EtherNet/IP port) the CPU Unit if the error recurs when the Unit is restarted.
What to do if Omron SYSMAC CJ1W-EIP21 reports a Verification Error (target non-existent)?
If the target registered in the device parameters does not exist, check the following items: * Is the registered node’s power supply ON? * Is the cable connected? * Is the cable damaged or loose? * Is there excessive noise?
What does Multiple Switches ON mean for Omron SYSMAC CJ1W-EIP21 Network Hardware, and how do I fix it?
If two or more software switches were ON simultaneously, or a second software switch was turned ON before a prior operation was completed, execute control bit operations one at a time.
What does Device Parameters Error mean for Omron Network Hardware, and how to fix it?
If the I/O Area set in the device parameters does not exist in the CPU Unit, or the EM Area was converted to file memory, download the Unit Setup from the tab pages of the Edit Parameters Dialog Box of the CX-Programmer and download the device parameters from the Network Configurator. If the error recurs, replace the EtherNet/IP Unit or (for a built-in EtherNet/IP port) the CPU Unit.
| Brand | Omron |
|---|---|
| Model | SYSMAC CJ1W-EIP21 |
| Category | Network Hardware |
| Language | English |
Introduces key features of EtherNet/IP Units and their capabilities, including data links and FINS communications.
Details the technical specifications for EtherNet/IP Units and built-in ports, including model and transfer specifications.
Explains the settings for unit number and node address using DIP switches for CS and CJ series units.
Outlines the overall procedure for installing and performing initial setup of EtherNet/IP units.
Describes the methods for setting the local IP address for the EtherNet/IP Unit or built-in port.
Details the TCP/IP and link settings required for network communication configuration.
Covers setting parameters for tag data links, saved in non-volatile memory.
Explains the structure and configuration of IP addresses for network communication.
Introduces tag data links for cyclic data exchange between devices.
Provides a comprehensive guide to setting up tag data links using the Network Configurator.
Details FINS message communications for OMRON products and their specifications.
Explains how to send explicit messages using CIP UCMM or DeviceNet EXPLICIT MESSAGE SEND commands.
Guides on adjusting communications load by managing bandwidth, RPI, and switching hub functions.
Describes the data processing time and I/O response time for tag data links.
Provides a step-by-step procedure for using the FTP server function.
Provides a procedure for using the automatic clock adjustment function.
Explains how to check device status using the Network Configurator's Device Monitor function.
Guides on using LED indicators and the 7-segment display for troubleshooting errors.
Offers systematic troubleshooting for common issues like ERR/ALM indicators and Ethernet problems.










