System Interconnection - Dell EMC PowerEdge MX7000 Field Service Manual

Table 19. Rear fan board description
Item Quantity
1 5
2 1

System interconnection

Power distribution
The Power Supplies plug into the Main DB to feed power to the rest of the system. There is a bus bar connection between
the Main and Vertical PDBs that can carry 255 amperes. V12V_AUX is only connected to the MM modules; no other modules
consume AUX power from the Power Supplies.
Power supply AC connection
The PSUs are accessed from the front, however the AC power cable connection is at the rear of the chassis. There are six C22
inlet connectors, three on the rear left, and three on the rear right side. Each PSU has an associated AC good LED located next
to its associated plug. If a PSU is not present, plugging in an AC cord has no effect. If a PSU is present, and the AC power
source is providing the appropriate power signal, the PSU drives the LED ON.
The C22 Inlet connectors allow for higher exhaust temperatures. The connectors are different than previous PowerEdge
offerings, a C20 to C21 jumper cord is required to connect to the inlet connectors.
Internal fabrics
This infrastructure has numerous communication paths or fabrics interconnecting the modules. The management fabric, referred
to as Fabric-D connects from each Management Module (MM) slot with a point-to-point link to each front slot and each IOM
slot. This fabric runs at 1 Gb/sec, an improvement over previous infrastructures which have run at 100 Mb/sec. In each MM
module, a switch is used to connect all the internal links, and external ports and a link to the MSM on each MM. A 10Gbit/sec
link spans the Main DB between the two MM slots for communication between those modules.
A second fabric in the infrastructure is Fabric-C. This fabric connects between the IOM C1/C2 modules and each front sled slot.
This fabric is intended for storage applications, for example SAS. Each front slot Fabric-C connection has two links, each x4 in
width to each of the IOMs, IOM_C1 and IOM_C2. This fabric is intended to support up to 24 Gb/sec SAS, and Fibre Channel at
32 Gb/sec.
USB
Each MM has a USB 2.0 link to the control panel. Only one port is operational at a time, based on which MM is active.
Front control panel and power control interfaces
Each MM displays the video to the front control panel Mini DisplayPort. The active MM drives the video. In addition to the DP
video, there are also individual links for USB from each MM to the right control panel.
The ECs are also connected to the control/status signals from each of the six power supplies. These tie to both the ECs and
therefore the status is monitored by both, however only the active MM shall drive the PS_ON_N signals. The PS_ON_N signals
in the PSUs shall function such that removal of the ECs (e.g., a service action) shall not cause the PSUs to shut off. To power
off a PSU, the EC must actively drive the signal HIGH as opposed to just allowing the signal to float high.
Power control of the IOMs and sleds is typically viewed as two separate steps, those being enabling AUX power and enabling
MAIN power. The AUX power on the modules is actually the 12V_MAIN from the PSUs, gated by hot-swap circuitry on the
module itself. For the MX7000 architecture, a reference or common circuit design for the hot-swap enable has been developed
to ensure consistency across modules. Each sled has a bi-directional SLED_PRES_PWR_ON signal that serves two purposes:
initially when plugged in a module it pulls this signal LOW, such that the MM can detect that a module is installed in the specific
64 Technology and components
Description
Smart Fan Connector – Card Edge 2 x 4 Signal, 2 x 2 Power.
Rear Fan Power and Signal Connector – STB 4P x 8S header.