Photographic Printer Control 1995

Objective: Retrofit manual photographic printer with automatic control and PC based user interface.

Requirements: Select control hardware within budget and implement automatic control of aperture, film winding, shutter, lens identification and color filters. Develop PC based user interface.

Results: Since previous developers failed to supply custom made microcontroller based control boards time and budget was constraint. I have picked PLC solution because of standardized available programming environment, easy maintenance (easily replaceable modules), wide variety of inputs and outputs and relatively low cost in comparison to previous custom approaches. Some of the more interesting solutions I have applied were:

- usage of ultrasonic sensor for aperture sensing , instead of regular resolvers,

- usage of barcode reader for verification of operator changeable lens.

Using PLC ladder logic I have implemented software for full printing cycle. All print parameters were applied through PC based user interface, which I implemented using Borland C++ under DOS environment.