An AS-Interface network comprises an AS-Interface master and up to 31 slave devices such as actuators, sensors, and display devices. Slave devices with a built-in AS-Interface chip connect directly to the AS-Interface network. Other slave devices act as an interface between conventional devices (actuators or sensors without the AS-Interface chip) and the AS-Interface network.
The DeltaV AS-Interface card has two ports and each port functions as an AS-Interface master. The AS-Interface master controls communications on the network by polling the slave devices, issuing commands, and receiving and processing replies from the slave devices. There can be only one AS-Interface master on the network. An AS-Interface network can support up to 124 inputs and 124 outputs. (Each slave can support up to four inputs and four outputs.) The maximum cable length anywhere between repeaters and extenders on an AS-Interface network is 100m.