It is possible to create loops in a network using the FieldDAQ device. To prevent these loops from disrupting the network, the FieldDAQ device implements the IEEE 802.1Q Rapid Spanning Tree Protocol (RSTP). Using this protocol, each FieldDAQ device can find the shortest path for incoming packets to reach the rest of the network. When multiple paths exist, this adds a form of redundancy. If a link fails, the protocol automatically switches to use the redundant link. This process can take several seconds in some cases.
To gain these benefits on external switches connected to the FieldDAQ device, IEEE 802.1Q (RSTP) must be enabled. All external switches must be configured to allow the FieldDAQ device to transmit RSTP packets, known as Bridge Protocol Data Units (BPDU). If any switch has a feature—such as “BPDU guard”—enabled, the port connected to the FieldDAQ device is disabled and communication is lost. Refer to the documentation for your external switch for information about enabling RSTP and disabling BPDU guards on the switch.