Architecture | Property Management System - Communication Interface |
The control codes used for the message texts are:
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Control Code | Hexadecimal | Function | |
Value | |||
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SYN | 32 | Synchronization code. | |
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STX | 02 | Indicates the start of a block. | |
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ETX | 03 | Indicates the end of a block. | |
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ENQ | 2D | Used as the start sequence code. It indicates a reception | |
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| request to the other side and a request to answer an infor- | |
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| mation block just sent. | |
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EOT | 04 | Indicates the end of transmission of a block or release of | |
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| the data link by the sender. | |
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ACK0 | 10, 70 | Used alternately, these indicate the positive acknowledg- | |
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| ment of an information block or a start sequence. | |
ACK1 | 10, 61 | ||
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NAK | 3D | Indicates the negative acknowledgment of an informa- | |
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| tion block or a start sequence. | |
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WACK | 10, 6B | Used as the positive acknowledgment of an information | |
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| block or start sequence and indicates that the receiver | |
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| temporarily cannot receive data from the sender. | |
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TTD | 02, 2D | Indicates that the sender cannot transmit the next infor- | |
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| mation block after the receipt of the answer to the previ- | |
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| ous information block sent from the receiver. | |
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RVI | 10, 7C | Indicates the positive acknowledgment of an information | |
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| block and asks the sender for sending rights. | |
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| 55 | Indicates the absolute beginning of the entire informa- | |
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| tion block. | |
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| FF | Indicates the absolute ending of the entire information | |
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| block. | |
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Page 12 |
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