Alcorn Mcbride V+ series, Руководство пользователя

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16-6 Appendix B
– Alcorn McBride Serial Control Protocols
The Show Controller sends a response byte of
0xAA
to indicate that it received
a valid command or 0x55 to indicate that it received an invalid command.
Here is the general form of an Alcorn 9 Bit Control message:
<source address>** <target address> <command opcode> <data bytes 1..n> <checksum>*
The <checksum> byte is the 8-bit sum of all previous bytes in the message
shifted right once. For example, if the sum of all bytes in the message is 0x5D
(or 01011101 in binary), shifting it right once will produce 0x2E (or 00101110
in binary). This byte is used for error detection and will cause the entire
message to be ignored if it is incorrect.
Here is an example Start Sequence #2 message sent from a PC (address 0xFF) to
a Show Controller whose address is 0x00:
0xFF* 0x00 0x18 0x01 0x0C*
Alcorn 8 Bit Control
Advantage: Easy to program
Disadvantage:
Not bullet-proof
Resources: C++ Programming Library available free to developers.
Alcorn 8 Bit Control uses the byte 0xF5 as a start of message delimiter. There is
no Mark or Space parity and any byte could have bit eight set high or low.
Here is the general form of an Alcorn 8 Bit Control message:
0xF5 <target address> <response> <length> <command opcode> <data bytes 1..n> <checksum>
The <response> byte tells the Show Controller what kind of response to send
back to the originating device. The response byte can take the following forms:

0x00 – Send no response back to the sender.

0x01 – Send a 0xAA (ACK) or 0x55 (NACK).

0x02
– Send the entire message back to the sender followed by an ACK or
NACK.
The <length> byte tells the Show Controller how many command and data
bytes are in the message.
The <checksum> byte is the 8-bit sum of all previous bytes in the message
(except the
0xF5
).
Here is an example Start Sequence #2 message (no response) sent from a PC
(address 0xFF) to a Show Controller whose address is 0x00:
0xF5 0x00 0x00 0x02 0x18 0x01 0x1B
Note: Alcorn 8-bit control cannot be operated at a baud rate greater than 19,200
baud.