19.2.2.2  Functionality
The Compact PCI makes 3.3V or 5V signaling in the backplane possible. The CBM
backplane and connected modules are 5V PCI-compatible.
Some pins on the Compact PCI connector are connected to the CAN bus, to be able to
communicate with CAN based modules.
If a modules self test discovers an error it informs other modules using the Internal Fail
signal IRF.
19.2.2.3  Design
There are two basic versions of the CBM:
• with 3 Compact PCI connectors and a number of euro connectors depending on
the IED case size. One Compact PCI connector is used by NUM and two are used
by other PCI modules, for example two ADMs in IEDs with two TRMs. See
figure 
509
• with 2 Compact PCI connectors and a number of euro connectors depending on
the IED case size. One Compact PCI connector is used by NUM and one is used
by for example an ADM in IEDs with one TRM. See figure 508
Each PCI connector consists of 2 compact PCI receptacles. The euro connectors are
connected to the CAN bus and used for I/O modules and power supply.
IEC05000516 V1 EN
Figure 508: CBM for 1 TRM.
Pos
Description
1 CAN slots
2 CPCI slots
1MRK505222-UUS C Section 19
IED hardware
1087
Technical reference manual