User's Manual

9XTend™ OEM RF Module - Product Manual v2.x6x
© 2010 Digi Internatonal, Inc. 29
KY (AES Encryption Key) Command
<Networking & Security> The KY command is
used to set the 256-bit AES (Advanced Encryption
Standard) key for encrypting/decrypting data.
Once set, the key cannot be read out of the mod-
ule by any means. The entire payload of the
packet is encrypted using the key and the CRC is
computed across the ciphertext. When encryption
is enabled, each packet carries an additional 16
bytes to convey the random CBC Initialization
Vector (IV) to the receiver(s). The KY value may
be “0” or any 256-bit value (= 64 hex digits =
32 bytes). Any other value, including entering ATKY
by itself with no parameters, causes an error.
A module with the wrong key (or no key) will receive encrypted data, but the data driven out the
serial port will be meaningless. Likewise, a module with a key will receive unencrypted data sent
from a module without a key, but the output will be meaningless. Because CBC mode is utilized,
repetitive data appears differently in different transmissions due to the randomly-generated IV.
NOTE: For international (non-U.S.) variants of 9XTend modules, the encrypti
on key is 128-bit
AES. The command operates the same except the key length is 16 bytes rather than 32 bytes.
This pertains to part numbers ending with -NA or -128 (the -NA and -128 suffix mean the same
thing), no matter what firmware version is loaded. This also pertains to the Australia version of
firmware 22xx, no matter what part number 9XTend it is loaded onto.
LH (Wake-up Initializer Timer) Command
<Sleep (Low Power)> The LH Command is used
to set/read the duration of time during which the
wake-up initializer is sent. When receiving mod-
ules are in Cyclic Sleep Mode, they power-down
after a period of inactivity (as specified by the ST
parameter) and will periodically wake and listen
for transmitted data. In order for the receiving
modules to remain awake, they must detect
~35ms of the wake-up initializer.
LH Command must be used whenever a receiving
module is operating in Cyclic Sleep Mode. The
Wake-up Initia
lizer Time must be longer than the cyclic sleep time that [as determined by SM
(Sleep Mode) parameter]. If the wake-up initializer time were less than the Cyclic Sleep interval,
the connection would be at risk of missing the wake-up initializer transmission.
Refer to figures loated under the SM command description to view diagrams of correct and incor-
rect configurations. The images emphasize that the LH value must be greater than the SM value.
AT Command: ATKY
Binary Command: 0x3C (60 decimal)
Parameter Range:
0 - (64 hex digits all set
to 'F')
Default Parameter Value: 0 (disabled)
Number of bytes returned: 2
Number Base: Always Hexadecimal
AT Command: ATLH
Binary Command: 0x0C (12 decimal)
Parameter Range:0 - 0xFF
[x 100 milliseconds]
Default Parameter Value: 1
Number of bytes returned: 1
Related Commands: HT (Time before Wake-up
Initializer), SM (Sleep Mode), ST (Time before
Sleep)