There are two 3FF SIM slots on the daughter board to support networking capabilities. One SIM slot is
externally accessible, with the other accessed on the bottom of the HSIO card.
M.2 B-Key 2
The lower B-Key slot is provided to allow support for B-Key form-factor PCIe and USB expansion
cards. Supported cards include 2042, 2260, and 2280 form-factors. The B-Key connector on the
Karbon 400 expansion card supports PCIe Gen 3 x1, USB 3.2 5Gbps, USB 2.0 devices. B-Key SATA
drives are not electrically compatible with this port.
SIM 1
The externally accessible 3FF SIM 1 slot is provided for networking capabilities on the B-Key 1 slot.
SIM 2
The internally accessible 3FF SIM 2 slot is provided for networking capabilities on the B-Key 1 slot.
This slot is on the bottom side of the Expansion card and is only accessible by removing the
daughterboard from the chassis.
RTC Battery
The RTC battery on the Karbon 400 expansion card is provided for redundancy with the main CMOS
battery to retain BIOS CMOS settings and maintain the real-time clock for the system. If the RTC
battery is low, CMOS settings will not be retained and you may receive an alert in the operating
system. Replacement batteries should be a UL listed type CR2032 3V cell.
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