A plurality of redundant devices each send a data stream, and one of the streams is selected to be forwarded, the selection being based on several factors

The present invention provides a system comprising a first master device 102, a second master device 104, a redundancy manager 106 coupled to the first and second master devices, and a slave device coupled to the redundancy manager. The redundancy manager receives a first data stream from the first master device and a second data stream from the second master and selects one of these devices to be forwarded to the slave device. The selection is based on a plurality of factors. The redundancy manager preferably includes a switch (130, Fig. 2). In one embodiment the plurality of factors are validity estimation of each of the first and second data streams, masterhip transfer commands from the first and second master devices, and timing considerations such as the length of time since the previous mastership command was received. In an alternative embodiment each of the factors is assigned a different priority, and the priority is taken into account when performing the selection. In one embodiment (Fig. 3) two redundancy managers 106A, 106B are provided and data is transmitted to the slave device on parallel lines 116A, 116B. The system is particularly suitable for use with remote oil and gas exploration and production apparatus.