ZP9D-115RM-LR Radio Modem
32
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 module by any means. The
entire payload of the packet is
encrypted using the key and the
CRC is computed across the cipher
text. 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.
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 modules 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 Initializer 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 located under the SM command description to view diagrams of correct
and incorrect 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 - (any other 64-digit hex
valid key)
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)