Weather the controller type is a 494 or 594 the software required for the controller to operate is similar.
All controller have:
2 x controller software diskettes.
2 x controller setup diskettes.
one of each being a backup copy ,if for any reason a copy gets damaged.
Check the diskette labels
The base controller software disk this is used only to boot controller for normal operation.
The second diskette base controller software backup is a backup copy, same as base controller diskette.
The Controller setup diskette is used only to perform diagnostics or configure the controller.
If the controller reports error 351 II 00 138 this message is the controller is being booted in normal mode with the setup diskette.
To resolve turn off the controller, replace the setup diskette with the base controller software, and power the controller back on.
Or if the controller is being booted with the setup diskette to configure or perform diagnostics the incorrect option was selected.
To boot in diagnostic or configuration mode.
Power on the controller without diskettes, when the display reads
003-02 1, to perform diagnostics change the 1 to a 0 ,then insert the setup diskette and press enter.
003-02 1, to perform a configuration change the 1 to a 2 insert the setup diskette press enter.