Author: Barbara Schmitz, CMO MEN Mikro Elektronik
For Ethernet, CompactPCI Serial CPCI-S.0 is physically based on the 10/100/1000/10GBase-T standards and supports both star and Ethernet Mesh architecture. While star architecture is fully sufficient for standard computers, a full mesh architecture is better suited for multicomputer systems. This way, redundant systems for safety-critical applications can be wired on the backplane via Ethernet. For this, several identical CPU boards are plugged into a standard backplane and combined with Ethernet switches. If a mezzanine slot is available on the CPU board, the CPU-and-switch combination can be accommodated in a single slot saving space and costs.
A special feature of these Ethernet mezzanines is that the CompactPCI Serial system connector P6 is not located on the CPU board but on the mezzanine. In contrast to previously known mezzanine standards, the signals are led directly to the backplane and do not have to be routed over the carrier board.
Another advantage of mezzanines is the flexible number of channels. The example described here uses a standard version with four channels. CompactPCI Serial supports up to 9 slots (standard backplane). This means that, for building a full mesh, one mezzanine with 8 channels will be chosen for all 9 boards, as 8 Ethernet interfaces are required on every board to enable independent communication with every other board.
In simpler multiprocessing systems where a star architecture is sufficient, the same mezzanine module is used - in this case only once plugged onto the system slot CPU.
Another possibility for using Ethernet at the front are CompactPCI Serial peripheral boards. These cannot only be operated in pure CompactPCI Serial systems, but also ensure fast connection in hybrid systems with a system slot according to CompactPCI PlusIO. For example, a Gigabit Ethernet board with 4 channels is connected to the backplane via a PCI Express x4 link. The Ethernet controller used supports data rates of up to 500 Mbits/s when all channels are operated simultaneously. The channels can also be configured as two redundant pairs. For rugged environments, the board is qualified for -40 to +85°C operating temperature and equipped with M12 instead of RJ45 connectors.
A board with 4 optical links (1000BASE-SX) offers exactly the same features. It supports SFP (Small Form Factor Package) transceivers, which are accessible on separate front panels, e.g. LC Duplex.