The short answer: It depends entirely on the PLC model.
User reports from forums (PLCtalk.net, MrPLC.com) are mixed: For every success story of a CPM2A being resurrected, there are two stories of a CS1G being turned into a doorstop.
If you cannot risk bricking your PLC or violating the law, here are the official, safe alternatives: Omron Plc Password Unlock Software V4.2
First, it is critical to understand that Omron Corporation does not officially release or endorse "password unlock" software. The version "V4.2" is a designation typically attached to third-party, reverse-engineered, or gray-market utilities designed to bypass or recover lost passwords on Omron PLCs.
These tools target specific legacy Omron series—most notably the C, CV, CS/CJ, and CP1 families. Version 4.2 implies a specific build that many users claim supports the following: The short answer: It depends entirely on the PLC model
Unlike official Omron software (CX-Programmer), which requires a valid password to upload or modify code, V4.2 tools attempt to interact with the PLC's firmware at a lower level or exploit known vulnerabilities in the FINS (Factory Interface Network Service) protocol.
The following is provided strictly for understanding the mechanics. Do not replicate on equipment you do not own or without disconnecting from the mains. User reports from forums (PLCtalk
Prerequisites:
Steps (as per the README_V4.2.txt included in the crack):
Common error: "Timeout Error 0x20" – This means V4.2 cannot force the PLC into programming mode. Check the physical DIP switch on the PLC (SW1-4 must be OFF).