Trio Motion Coordinator MC216 - Network Specification

11-12Fibre-Optic Network
Network Specification
Trio Motion Technology
Network Specification
Message Format
Each message is constructed of a header character, the message, a cwt. check
(on direct variable transfers only) and an end of message character.
Note: • Address of receiver is in the range 1 (for next node) to 15 (15th node on
network). This is different to the node addressing used by Trio BASIC and is for
internal use only.
• The number of message bytes (n) is determined by the message type as
described below
• CRC bytes are used for direct variable transfers (message type 2)
Network Protocol
The sender places the message on the ring and assumes it arrives at its destina-
tion. Any packet checking must be done by the user because the nodes have no
knowledge of the size of the net. Each successive node decrements the address
by 1 and if the result is greater than zero it re-transmits the message with the
decremented address in the header and end of message. If the result is zero then
the message is for that node and is processed as necessary. The re-transmission is
invisible to the user.
Message Types
The message types described here are for internal use only and are different to
those used by the SEND command
Bit 7 6 5 4 3 2 1 0
Header
1 <Address of Receiver> <Message Type>
Message (n bytes)
0 <----------- Character Information ---------->
CRC (byte 0)
0 <--------------- Bits 6..0 of CRC -------------->
CRC (byte 1)
0 <--------------- Bits 14..8 of CRC ------------>
End of Message
1 <-Address of Receiver> 0 0 0
0
End of message character.
1
Character transfer. Message can be 1 byte long, e.g. a key press from a keypad,
or several bytes long, e.g. PRINT statement.