User`s guide

Power and Cooling Systems
4.1.7 Power System Signals
Power system signals are partitioned so that a failure of one power supply
shuts down only the XMI side and a failure of another power supply shuts
down only the VAXBI side.
The power system signals are described in Table 4–2.
Table 4–2 Power System Signals
Name Origin Destination Description
PNL RESET L Control panel XTC Asserts when the control panel Restart button
is pressed. Causes the XTC to start the reset
sequence.
STANDBY CMD L Control panel H7206-B Asserts when the control panel upper key switch
is in any position except "0."
ON CMD L Control panel H7206-B Asserts when the control panel upper key switch
is in either the Enable or Secure position. Applies
DC power to entire system.
PB REQ L Control panel H7206-B, then
from H7206-
BtoDEC
power bus
and AC power
controller
Asserts when STANDBY CMD L asserts to close
a contactor in the AC power controller, applying
AC power to H7206-B and DC power to cooling
system and memory. Controls all peripherals tied
to the DEC power bus.
DEC Power Bus Control panel H405 Safety Extra Low Voltage (SELV) circuit that
allows the system to turn other equipment on and
off.
DC OK H H7206-B XTC Asserts to indicate that the DC outputs from
the power regulators are OK. The XTC power
sequencer uses this signal to start the power-up,
power-down sequence.
AC OK H H7206-B XTC Asserts to indicate that the AC input voltage is
adequate. It deasserts when the H7206-B’s 300V
DC output level reaches a level that guarantees
4.2 milliseconds of acceptable 300V DC prior to
the deassertion of DC OK H. The XTC power
sequencer uses this signal during the power-up,
power-down sequence.
BBU STATUS BBU Control panel Controls the green Battery LED indicating
condition of the BBU.
MODULE ENABLE L BBU H7206-B Asserts to indicate that the BBU is supplying
power.
BATTERY BACKUP
ENABLE H (BBUE H)
H7206-B BBU Asserts before the BBUR H pulse indicating the
need for battery power. Deassertion of this signal
causes the BBU to stop supplying power.
BATTERY BACKUP
AVAILABLE L (BBUA L)
BBU H7206-B Asserts to indicate that battery backup is
available to system with a minimum of a 40%
charge level.
4–5