Description
Most of the Praesideo system units have Bosch PRS-FINS plastic fiber optic interfaces. Plastic fiber is used to interconnect nodes which are less than 50 meters apart. For distances of more than 50 meters, glass fiber optic cable is used. A fiber interface converts from plastic to glass fiber, and vice versa. The fiber interfaces have a power supply input to provide power to remote network sections, and two control inputs. The control inputs can pass on supervision information about the power supply connected to the fiber interface.
These Bosch PRS-FINS units interface glass fiber optical cable with plastic fiber optical cable, and support redundant wiring topology. In many applications this is necessary, because glass fiber can bridge much longer distances than plastic fiber. Any conversion to glass fiber must be converted back to plastic fiber before other Praesideo units can be attached, since they all have plastic fiber interfaces. This means that these units are always used in pairs. Each interface can use an external 48 VDC power supply to provide power for itself, as well as for remote parts of the network. If there is no external power source, the interface uses power from the network controller.
The PRS‑FIN and PRS‑FINS have two control inputs. These can be used to accept e.g. the fault output of the external power supply (UPS), allowing the units to monitor the power supply and report faults to the network controller. The fiber interfaces have two LEDs for diagnostic purposes.
The PRS‑FINNA is the same as the PRS‑FIN except that it has no network node address. This has the advantage that the unit does not occupy one of the 60 possible addresses in the network. It also has the disadvantage that without an address, it is not possible to access the status of the two control inputs, as it is with the PRS‑FIN.
The PRS‑FINS is the same as the PRS‑FIN, except that it accepts single‑mode glass optical fiber instead of multi‑mode glass optical fiber. However, this does not increase the maximum permitted cable length of a Praesideo network.