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Quamatic Communication Protocol
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Communication with Quamatic hardware is effected by the originating party issuing a command and with the receiving party responding.

The exchanged messages have the following format (so called "Double DLE"):


where <DLE> is the "Data Link Escape" ASCII character (decimal 16), <STX> is the "Start of TeXt" ASCII character (decimal 2), <COMMAND> is a command string, <DATA> is the exchanged data (if any), <CHECKSUM> is the checksum byte and <ETX> is the "End of TeXt" ASCII byte (decimal 3). If a byte in the <DATA> block has the value of the <DLE> character it is repeated (ie transmitted as <DLE><DLE>), so that the starting and closing character combinations are unique.

Thus, on detection of a <DLE><STX> string, the receiving hardware prepares for the reception of a new message (being a command or the response to an issued command). On detection of a <DLE><DLE> string, only one <DLE> byte is entered in the buffer and on receiving a <DLE><ETX>, the message is closed. Processing of the received message starts immediately after its integrity has been checked. (The <CHECKSUM> byte equals to the simple sum of the message bytes).

As Quamatic nodes can be chained, they are addressed by their address byte. Thus, the <COMMAND> string to a node or a satellite in the network carries the node address byte and the command character. The <NUL> address byte (decimal 0) is reserved for broadcasting network-wide commands and messages. The following are typical commands implemented in most hardware:

All Quamatic hardware, unless specifically stated, handles MSB (Most Significant Byte) first data.

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