, you can perform a manual "clear-all" operation. This typically involves placing the PLC in STOP mode and following specific hardware sequences, such as manipulating DIP switches or removing the memory capacitor, as detailed in the DirectLogic Hardware Manuals .
You are a professional. Before using any method from this article, ask three questions:
: Older firmware versions for certain Koyo/DirectLogic PLCs had vulnerabilities (like CVE-2022-2003) that allowed attackers to extract the password over serial or Ethernet using specific byte sequences. While these are generally patched in newer units, they may still work on legacy field equipment.
If you are using the newer Koyo-built CLICK series (via CLICK Programming Software), you are in luck. The CLICK software has a built-in "Forgot Password" feature that generates a temporary override code based on the CPU's serial number. You need to contact AutomationDirect support with that code—they will give you a temporary bypass if you prove ownership.
A search for "Koyo PLC password unlock" often yields third-party software tools, hex-editing tutorials, or specialized service providers claiming instant unlocking. How Text/Hex Editing Works on Legacy Models koyo plc password unlock
Once you regain access, implement a strategy to ensure it doesn't happen again:
Store PLC passwords in a company-wide manager like LastPass or Bitwarden.
Losing or forgetting a Koyo PLC password can halt production, delay maintenance, and cause significant downtime. Whether you are dealing with a legacy Koyo DirectLOGIC controller or a modern Productivity Series PLC, regaining access to your ladder logic is critical.
The standard format for a "multi-level" password, which allows data reading but blocks program access, is a capital letter "" followed by seven numeric digits (e.g., A1234567). If an administrator has changed the prefix, the password might start with another character (B through Z). Knowing whether your PLC is using a standard numeric password or one beginning with a specific letter is the first step in unlocking it. , you can perform a manual "clear-all" operation
If keeping the existing program inside the PLC is not a priority, you can perform a factory reset to regain access to the hardware.
While technical vulnerabilities exist in older KOYO PLCs, exploiting them without authorization is illegal and dangerous. Legitimate users have clear paths to recovery via manufacturer support or hardware replacement. This paper underscores the need for better access management in industrial environments.
Before performing a reset, try these common default or "guessable" passwords: (Default for CLICK Ethernet and CLICK PLUS CPUs). Company Name Project Number Machine Model Number (no password). 2. Resetting the CLICK Series
"Recovering Access to Legacy KOYO PLCs: Password Mechanisms, Vulnerabilities, and Authorized Recovery Methods" Before using any method from this article, ask
Review access control and change management
Open the file in a text or hex editor if the software itself prompts for an offline password. In some older software versions, security configurations are visible within the project properties or configuration files. 2. Factory Reset (Clearing Memory)
Interestingly, the LCD panel has its own separate password protection system that restricts changes to the clock, date, and V-memory values. To change the LCD password, technicians can navigate to Menu 5 (). To remove an existing LCD password, entering 8 zeros ( 00000000 ) will clear the protection.