Abstract: A multidrop communications system for transferring data to a plurality of devices, comprises an optical fibre having first and second ends, a plurality of light sources for producing light of different respective wavelengths, modulation means to modulate light from each light source to encode respective data thereon, the modulation means outputting a plurality of modulated light components having said respective wavelengths, an optical multiplexer for multiplexing said modulated light components onto said first end of the optical fibre using wavelength division multiplexing, an optical demultiplexer connected to the second end of the optical fibre for demultiplexing light therefrom into a plurality of components having respective wavelengths, demodulation means for demodulating each of said components to extract said respective data, and means for transferring the extracted data to different respective target devices.

Abstract: An electronics module for a well installation comprises a wireless receiver for receiving data and/or software from an external source.

Abstract: An electronics card for an electronics module comprises a wireless transceiver for communication with a second wireless transceiver external to the card. In addition, an electronics module comprises such an electronics card.