Type of detected event is encoded into the
”Alarm code”
variable (OID 60 - TRAP CODE), where value of
variable determines event type. Current version of the NB-K430 module supports sending of one type of event -
information about the
module reset
, with additional information about its cause.
Fixed part of the message
is comprised of the first six variables, that are the same as in INFO message. The
only difference is that ”Message type” (OID 63) is set to
”5”
value, what is a flag of
TRAP
type of message.
After this part of the message there is always
”
Alarm code”
variable (OID 60 - TRAP CODE), carrying infor-
mation about the event type. ”RESET” type of event is assigned by
value ”0”)
.
”
Alarm code” variable can be followed by one or several variables specifying event parameters.
”
RESET” type of
event is followed by variable of
”
Reset code”
type (OID 14 - RESET CODE), carrying information about the
reset cause. In the NEP coding table there are following types of reset:
- value ”0” - Cold start
- value ”1” - Warm start
- value ”2” - Watchdog reset
- value ”3” - Error reset
- value ”4” - Power reset
Example of ”TRAP” type message with information about the reset of ”Warm start” type (caused by regular
command):
OID
Index
OID Name
Description
Example
63
Message type
TRAP type message
5
2
Device Type
Type name by manufacturer
850
3
Device Subtype
Device modification
1
4
Manufacturer No.
Device identification (IMEI)
12
Uptime
Time from last reset (sec)
0
61
Sequence No
unique message number
60
Trap code
RESET alarm code
0
14
Reset code
Reset code WARM START
1
3.4.4
Encryption of messages
Encryption of messages by AES key can be activated by setting of encryption key with using of
”ekey”
command
(see paragraph
”
Commands for setting of message broadcasting system”). Encrypted message is in its first
variable (
”
Message type”) designated as
”
Encrypted message” (OID 63 value is
127
- ENCRYPTED MESSAGE).
The first six variables of the message are always sent unencrypted, because they carry data that are necessary
for decryption. All other variables are encrypted by
block cipher CFB
and they are transferred in the message
as encrypted value of one variable, designated as
”
Encrypted part of the message”
(OID 19 ENCRYPTED
BLOCK).
Structure of encrypted message has following structure:
OID
Index
OID Name
Description
Example
63
Message type
ENCRYPTED MESSAGE type
127
2
Device Type
Type name by manufacturer
850
3
Device Subtype
Device modification
1
4
Manufacturer No.
Device identification (IMEI)
12
Uptime
Time from last reset (sec)
186552
61
Sequence No
unique message number
19
Encrypted block
Encrypted part of the message
rest of variables
In the encrypted part of message there are all other variables encrypted by block cipher. The first variable in the
encrypted block is always ”Message type” (OID 63 MESSAGE TYPE), that carries an information, whether the
type of message is INFO (value 6), or TRAP (value 5). Other variables follow in same order (and structure), as in
unencrypted message (starting with seventh variable to the end of message).
NB-K430
25
