SAINT
Keyword 2000 to
01/20/04
Page 12 of 20
4.4.2Transmitted Keyword 2000 Messages
The following is the format for sending a Keyword 2000 message:
Header | SID (Service Identification Byte) | N Data Bytes |
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28h | Byte 2 | Bytes 3 ¾ (2+N) |
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The above information is used to form the following message which is sent onto the Keyword 2000 bus (with Length Byte not included in the Format Byte):
Format | Target | Source | Length | SID | N Data Bytes | Checksum |
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Byte 1 | Byte2 | Byte 3 | Byte 4 | Byte 5 | Bytes 6 ¾ (5+N) | Byte (6+N) |
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The above information is used to form the following message which is sent onto the Keyword 2000 bus (with Length Byte included in the Format Byte):
Format | Target | Source | SID | N Data Bytes | Checksum |
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Byte 1 | Byte2 | Byte 3 | Byte 4 | Bytes 5 ¾ (6+N) | Byte (5+N) |
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Also, the SAINT will check to see if the bus is “initialized” and if necessary will send the Fast initialization sequence (transmit Wakeup Pattern of 25msec logic low and 25msec logic high followed by a Start Communications request message 81 11 F1 81 04). Refer to the “Keyword Protocol 2000 Data Link Layer Recommended Practice” section 5.1.5.3 for more information.
Currently, only the Fast Initialization sequence is supported. Future initialization sequences will be added as needed.
