3Com 8807, 8814, 8810 manual MBUS Introduction

General Architecture 15

Table 2 describes typical equipment configurations and specifications of external PoE power system.

Table 2 Typical equipment configurations and specifications of external PoE power system

Item	Description
Physical dimensions (H x W x D)	177 x 486 x 320.5 mm (7.0 x 19.1 x 12.6 in.)
System controller	One
Rectifier	Two NP2500UAC (required) + one redundant
	NP2500UAC (optional)
AC accessory	Three AC inputs and switches
	Three-phase AC voltage detection circuit
	Input voltage range: 90 to 290 VAC; rated voltage
	and current: 250 VAC, 20 A
DC accessory	A single DC output, with max output current of
	93 A
Max power consumption	4500 W

The external PoE power system has monitor function. It provides one system monitoring module, one RS232 and two RS485 monitoring interfaces. The system monitoring module reports the running information of the PSUs in the system to a fabric through RS232 or RS485 interface and indicates alarm status by the alarm LED (ALM). You can connect cables to the interfaces from the front as well as the rear of the frame.

n	The external PoE power system for the Switch 8800 Family only supports the
	RS485 monitoring interface.
	Table 3 LEDs of external PoE power system

			Normal	Abnormal
LED	Label	Color	state	state	Abnormal reason
Input power LED	AC	Green	ON	OFF	Loss of AC input power, or blown
					fuse
Output power LED	DC	Green	ON	OFF	No DC output from PSU
Fault LED	Fault	Red	OFF	ON	Irreversible fault occurred in PSU
Running status LED	RUN	Green	ON	OFF	PSU shutdown or PSU running
					trouble
Alarm LED	ALM	Red	OFF	ON	Loss of AC input power,
					under-voltage or over-voltage
					input, under-voltage or
					over-voltage output, or PSU fault

MBUS Introduction

The MBUS is a service-independent maintenance and test bus. No service traffic goes through the MBUS. The shutdown and reset of the MBUS does not affect the services on the switch, and faults that have occurred on modules do not affect the MBUS.

Through the MBUS, the system instructs the MBUS modules on individual cards to power on/off the cards one by one in turn, thus prevent power surging. The MBUS module software must support online upgrade.