The 3U crate is a main component of the Distributed I/O Tier hardware kit. The enclosure is assembled using 3U sub-rack components compatible with the IEC 60297-3 and IEEE 1101.10-1996 mechanical standards. These are low-cost aluminum elements available in the products portfolio of all major crate vendors. The crate provides:
support to host Rear Transition Modules (RTMs) - the RTMs are usually fully passive boards that provide an interface with external equipment through a direct RTM connector to the corresponding Peripheral Board
two power supply slots (two power backplanes) to host dual modular redundancy power supplies in load-sharing configuration
optional 1U fan tray that can be mounted either below or above the main 3U crate
DI/OT crate 19" rack variant:
DI/OT crate tunnel variant:
DI/OT main backplane
The DI/OT main backplane is a KiCad design compatible with the CompactPCI Serial standard. It provides 9 slots (1 System Slot and 8 Peripheral Slots) and the support for RTMs.
DI/OT main backplane(front view):
DI/OT main backplane topology:
The backplane provides:
a star topology of 144 LVDS lanes in total (18 LVDS lanes per Peripheral Slot) used as differential or single-ended I/Os to implement communication between the System and Peripheral Boards. Out of those, 1 LVDS lane
per Peripheral Slot is reserved for the distribution of low-jitter clock and 2 LVDS lanes are designated for high-speed communication
the Reset line driven by the System Slot to reset all the Peripheral Boards
a set of 5 multidrop lines (multidrop IRQs) can be used as interrupt lines of 5 priorities, or for any
other one-to-many signaling.
a star of single-ended presence detection signals and a service I2C bus (shared among all the slots)
distribution of two auxiliary voltages to all Peripheral Slots.