Section 8 – Automation Communication Formats
8–25
8.8 SK9000
Protocol
The following sections describe the computer protocol.
8.8.1 Data String Description And Special Characters
Table 8–26: Data String Description
Data Element
Byte(s)
Occupied
Description
Identifier
1
The first byte of a message is the identifier. This byte is always $01 or $27.
$01 = a system message
$27 = a call from a panel
Date
2-7
The next 6 bytes are the date in MMDDYY format, where each byte
contains the ASCII code for the digits 0-9.
Separator
8
The byte after the date is a separator. It will always be $22.
Time
9-12
The time, in the 24-hour military format, at which the MX8000 receives the
message, occupies bytes 9-12. Each byte contains the ASCII code for the
digits 0-9.
Separator
13
The separator $22 occupies byte 13. The actual call or message data
follows this byte.
Format number
14
In a call, byte 14 is the format number, which indicates the format of the line
card the call was received in.
Line card number
15
Byte 15 is the line card hunt group number. In some cases you may need to
decode the hunt group number. If the hunt group is set to 00 then the
number sent in byte 15 is equal to the line card number. (See section
5.5.2.5 for more information.)
Separator
16
Byte 16 is a separator that precedes the actual call or message data. The
data will be $05.
Account #
Variable,
beginning at
position 17.
Can be 1-8 bytes long. ASCII codes for the digits 0-9 and characters A-Z
are acceptable data.
Separator
Variable
The separator $22 separates the account number from the first event.
Event Data (Alarms and
System Messages)
Variable
Alarms can be up to 11 characters. Multiple alarms are separated by $22
(ASCII code for the double quotation mark).
System messages, (indicated when the first byte of the message is $01),
are always sent separately. For example, if two line cards have a problem
at the same time, the MX8000 will send one message for each line card.
Validation Byte (V-Byte)
1 byte. Follows
event data.
Error-check byte. (See section 8.8.6 for more information.)
End of Message
Indicator (carriage
return)
1 byte. Last
byte in call.
This byte is always $0D and indicates the end of the message.
Table 8–27: Special Characters Used in the Protocol
Hex Value
Meaning
$27
If this character is the first byte in a string, the data that follows is an actual call
from a subscriber (rather than a system message).
$01
If this character is the first byte in a string, the data that follows is a system
message (rather than a call from a panel).
$22
Separator. Separates the date from the time; separates the time from the data that
follows; separates multiple events occurring in the same message.
$05
Separates header information from account # in messages from subscribers.
$23
Bad data. This marks a block of questionable data.
$21
Bad data mixed with good data in the same call. This marks a block of good data
that follows a block of questionable data.
$2C
Long call; more data to come for this call in next block.
$0D
Indicates end of message.
$2A
Listen in begins.
