Since PROFINET is based on standard unmodified Ethernet, it gives users all topology options: cabled topologies and wireless connections(via Bluetooth or Wi-Fi). The table below summarizes the benefits and challenges of different PROFINET topology configurations.
|Line||Most PROFINET devices have at least two ports, with such ports being part of a built-in switch in the device. Built-in switches allow users to connect devices in a line topology without external switches.||
|Star and Tree||Built-in or standalone switches allow for star/tree topologies.||
|Ring||PROFINET allows you to implement a ring topology by managing it with two defined media redundancy protocols: Media Redundancy Protocol (MRP) and Media Redundancy for Planned Duplication (MRPD).||
|Wireless||Wi-Fi or Bluetooth can become part of a PROFINET network backbone.||
 Each switch that is placed between a device and its controller introduces a delay in the data transfer. The number of switches between a controller and a device is called the line depth. A large line depth will add delay, which must be considered when planning the network topology.
,  MRP and MRPD enable the connection of devices based on ring topologies.
MRP: If the transmission link in the ring is interrupted, the ring manager immediately activates the alternative communication path. The recovery time is in the millisecond range.
MRPD: Each sender in the ring sends two equal frames to the receiver in opposite directions around the ring. In case of a network failure, one frame will still arrive at the receiver. MRPD ensures non-stop connectivity with a recovery time of zero.
Read the full Topology White Paper HERE: