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DACS App Note

Configuring a DACS with Multiple Removable Drives (#15)

The purpose of this application note is to provide some general information regarding the configuration of a system with multiple removable drives. A specific instance of this is a J.F. Taylor project, NAWC1-10. The ILP in this project had a 2.5" removable, a 3.5" removable and a 3.5" fixed drive. The system would only need to support 1 removable drive installed at a time.

The two different sized removable drives were necessary in this platform because the 2.5" removable is being phased out of production. The 3.5" removable drive will soon be our standard. Therefore, this chassis with the dual removable drives will allow this customer to make the transition from one format to another.

The CPU used was an HM systems 166 MHz Pentium, and both the primary and secondary IDE controllers were used. The two removable drives were ganged together and attached to the primary controller connector and the fixed drive was attached to the secondary controller connector. The system would boot from whichever removable drive was installed when the system was started.

Both of the removable drive carriers, and the fixed drive are jumpered to act as system masters. This is due to the fact that the removable drives are the master drive in another system. It is not possible, without custom modification, for the drive to act as both master and slave. If both removables are present at the time of system startup, a hard drive controller conflict results and the system locks up. If the system is started with no removable drive installed, the system will attempt to start from the fixed (D:) drive, but will be unsuccessful. The fixed drive is set as the "Sec Master" under the "Standard CMOS Setup" in BIOS. The removable drives are set as the "Pri Master" in the "Standard CMOS Setup".

The fixed drive merely acts as a storage spot for information to be transferred from one hard drive to the next. The models are developed on one removable drive, moved to the fixed drive, the system is shut down, the drives are swapped, the system is started back up and the models/files are moved from the fixed drive to the newly installed removable drive.

BIOS settings are a concern when swapping hard drives in this fashion. In this case, the "Pri Master" was set to "AUTO" under the "Standard CMOS Setup" and the system recognized both hard drives even though they were different types. If one of the removable drives was not recognized by the AUTO function, then the Pri Master settings would have to be manually entered every time that a different drive type was installed.

Another pitfall of this system arrangement is that every hard drive that is installed in this development system must have an options file installed that is keyed to the development platform's E-net. Otherwise, when Model Builder is started the message "No valid options file for this Model Builder version" is displayed. The options file, keyed for the development platform, can be stored on the fixed drive. When the new drive is installed, the options file can be copied into the new drive's C:\mbuilder\bin directory. Model Builder will automatically search for and select the options file that is keyed for its particular platform.