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ViSi-Genie Magic: How to Read a File


Number 4D-AN-00161
Difficulty Medium
Supported Processors PICASO, DIABLO-16, PIXXI-28, PIXXI-44
Supported Environments ViSi-Genie


In the past it was not possible for a host to access files stored in the uSD card of a display module loaded with a ViSi-Genie application. With Workshop 4 Pro it is now possible to accomplish this through the use of the Magic Object. The Magic Object is one of the objects available under the Genie Magic pane. It is actually a 4DGL function which allows users to program the display to handle bytes received from an external host. The user, for instance, can create a Magic Object that waits for 14 bytes from the host. The 14 bytes can contain an instruction byte, followed by a null-terminated 8.3 format filename (e.g. "datalog1.txt"). The instruction byte can be a file read, a file write, a file append, etc. Upon receiving a file read instruction together with the filename, for example, the display module will send back the contents of the file (if it exists) to the host. The ViSi-Genie example project “FileAccess.4DGenie” is an example of the above application.

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