A specialist with legacy tools can extract your PLC program, convert it to a modern platform, and provide you with a PDF printout of the ladder logic. This is often cheaper than the downtime caused by a bad software download.
Find an old industrial PC (Pentium III or earlier) with a real COM port and a fresh install of MS-DOS or Windows 95/98. This is the most reliable method for online editing.
If you are struggling with the download or installation, consider these alternatives:
| Problem | Likely Solution |
| :--- | :--- |
| "Runtime error 200" | This is a division by zero timing bug in old Borland Pascal compilers. Use a TSR patch like PATCH200 or run in DOSBox with appropriate core settings. |
| Serial communication fails | MEDOC 2.4 expects COM1 at IRQ 4, address 3F8h. Ensure your USB-to-serial adapter emulates these standard settings. Use the SC-09 programming cable. |
| File won't open | The .PLC file might be corrupt. Try opening with a hex editor to check for consistent data. Alternatively, use MEDOCSAVE and MEDOCLOAD utilities (if available). |
| Screen glitches | DOSBox config: Set output=overlay or output=opengl. Disable hardware scaling. |
Mitsubishi’s modern software can convert many legacy MEDOC projects. You can:
Search for the following filename pattern (typical release):
MEDOC24.ZIP
MEDOCV24.EXE
MEDOC_24.7z
The package usually includes:
Size: ~1–2 MB compressed.
MEDOC v2.4 is designed specifically for the following hardware families:
Dedicated automation forums have download sections for legacy software. Always scan any downloaded file with at least two antivirus engines before running.