NAL Research Corporation (TN2009-25-V1.0)
13
2.
Security Requirements for Cryptographic Modules,
Annex A: Approved Security Functions
for FIPS PUB 140-2, US Department of Commerce, National Institute of Standards and
Technology, February 19
th
, 2003.
9.0 SELF-MONITORING TO PREVENT MODEM LOCK-UP
The 9522B RF board can sometimes ‗lock-up‘ when being inactive over a long period of time (a day or
longer). The only way to recover is to power cycle the ISU. The A3LA-XM has safeguards put in place with a
watch-dog timer to keep the 9522B RF board from locking up. These were done by having another micro-
controller in-line with the serial communications, monitoring the communications and making sure the
9522B is responding correctly. Each of the safeguards is enabled by default. Below is a description of each of
the four safeguards. These safeguards were also employed on the A3LA-MPT and are the same as those
used on the A3LA-MPT version 1.2.0.
Check When Not in a Data Call
: The micro-controller has a timer that is reset every time a character
arrives from the 9522B board. The timer is set to end every 2 minutes. A3LA-MPT versions earlier than 1.1.0
had the timer set to every minute. When the timer expires the micro-controller will check to make sure the
9522B is still responding by sending it an AT command. If the 9522B responds it starts the counter over
again. If there is not response it power cycles the 9522B. This can be enabled or disabled with the ^MPTNC
command.
Check When in a Data Call
: The micro-controller has a timer that is reset every time a character arrives
from the 9522B board during data calls. The timer is set to end every 4 minutes during data calls. A3LA-MPT
versions earlier than 1.1.0 had the timer set to every 2 minutes. When the timer expires the micro-
controller will check to make sure the 9522B is still responding by sending it the +++ sequence. If the
9522B responds it returns to the data connection and starts the counter over again. If there is no response
it power cycles the 9522B. This can be enabled or disabled with the ^MPTDC command.
Hourly Registrations
: The micro-controller will force manual registration by implementing the command
AT+COPS=1 every hour to make sure the 9522B stays registered. Before forcing registration it will look for
a period of inactivity. If one cannot be found, it will force registration while ignoring input from the DTE.
Forced registration will not occur during a data/voice call. This can be enabled or disabled with the ^MPTFR
command.
Forced Power Cycles Every 24 Hours
: The micro-controller will force a power cycle of the 9522B board
every 24 hours. Before power cycle the RF board, it will look for a period of inactivity. If one cannot be
found, it will force power cycle regardless of any events occurred over the serial port. Power cycle will not
happen during a data/voice call. This can be enabled or disabled with the ^MPTFP command.
10.0 MOUNTING RECOMMENDATIONS
The A3LA-XM has four features on its bottom surface that can aid in its mounting (see Appendix E).
These four features are pre-drilled at a minimum depth of 0.25 inch to accept 6-32 thread type. If the A3LA-
XM is to be used in a harsh environment with exposure to high humidity or water, the mating of the multi-
interface connector must be further sealed to protect from moisture infiltration. It is recommended that a
bead of RTV silicone sealant be placed on the connector mating to the A3LA-XM‘s multi-interface connector.
A material similar to Permatex 16B should be used.
