Emerson AXP640-AC2-110VAC, Installation & Use Manual

Page: 150 / 190

Shelf Management Alarm Module
AXP640 Installation and Use (6806800M24E )
150
z
Cross connected redundant ShMM-1500R status 1 input (SHMM_STATUS1_R) and output
(SHMM_STATUS1_L)
z
Active output (ACTIVE#) that can be used on the ShMM-1500R carrier to enable interfaces
that must be exclusively driven by the active ShMM-1500R
z
Bi-color status LED
The cross-connected ShMM-1500R status signals are asynchronous serial bit streams that are
transmitted to the peer-ShMM by the FPGA and communicate the following information:
Health status, Switchover Requests, PRES_R state, Active state, watchdog timer status, parity
and other data. An identical copy of the bit stream is also sent on the redundant ShMM-1500R
status signal. This information is used to ensure that only one of the two connected ShMM-
1500Rs goes into active mode at a time.
Figure 7-3 on page 151 shows the HRI of the ShMM-
1500R.
As shown in the figure, the ShMM-1500R HRI incorporates a hot-swap buffer (IDT
QuickSwitch), which isolates the interface from the peer ShMM prior to FPGA configuration or
when the ShMM-1500R is powered down. The QuickSwitch device is guaranteed to be disabled
(open) when unpowered and does not have a low impedance path from any of the signal pins
to the power or ground rails. Hence, the device prevents an unpowered ShMM-1500R from
loading down the HRI of the peer ShMM-1500R. It also prevents a carrier from detecting the
ACTIVE# output as a zero; that is, active, during a ShMM-1500R power cycle or a ShMM-1500R
power supply failure.