P-NET Redundancy
P-NET redundancy provides an additional communication network path between a number of M36 clusters, where under normal operational conditions, one network is redundant.
Each P-NET must be of the bus topology (terminated) type, maximum length 600 metres.
Each of the individual networks within a redundancy installation should be regarded in the same way as a traditional network, and follow the same rules as P-NET bus topology networks.
A redundant type network must only contain BM 010 base modules for mounting PD 662 electronic modules.
To achieve the full benefit of the redundancy network topology, the two P-NETs should follow different installation paths. This will help to prevent both P-NET cables being damaged during the same incident.
![](https://www.proces-data.com/wp-content/uploads/2018/01/redund_topology.gif)
Termination
The BM 010 modules at the end of each network must be configured for termination. Mounting the BM 010 at the right most position in a cluster, it will allow easy access to the jumpers in the base module.
When the BM 010 is used as termination module the P-NET #1 must be connected to the 1’st terminal column from the left (terminals: 1, 5, 9), and P-NET #2 must be connected to the 3’rd column from the left (terminals: 3, 7, 11).
PD 662 cluster position
Due to the ability of the PD 662 to shutdown the Light-Link port if it detects errors in the port, it is recommended to position the PD 662 at one end of a DIN rail. This ensures that M36 modules will be connected only on one side of the PD 662 – see figure.
If the PD 662 is not placed at the end, it will not be possible to dismount the M36 modules next to the PD 662 without breaking the P-NET Light-Link communication, in the event that the PD 662 has shutdown the P-NET Light-Link port.
Recommended installation
![](https://www.proces-data.com/wp-content/uploads/2018/01/image003.gif)