FLX-E Operations Manual Rev F
Page 38
Table of Contents
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Byte 3 = 0x03
end of message character
FLX-E Response
Byte 0 = 0x02
start of message character
Byte 1 = 0x16
command code
Byte 2 = 0xXX
channel number
Byte 3 = 0xXX
current mute state (0 = mute off, 1 = mute on)
Byte 4 = 0x03
end of message character
13
Appendix C—FLX-E Ethernet Communications Interface (API) – Rev 2.0
All data is sent in binary, not ASCII format.
All floating-point data is sent as a 32-bit (4-bytes) IEEE floating-point number, little-endian format.
Each command is started by a Start-of-Message byte with a value of 0x1E.
The next two bytes are the integer length of the payload section, sent little-endian format.
Following the payload length bytes is a one-byte message sequence number. This is an 8-bit
number controlled from the host-side application. In the Stewart Audio FLX-E application, this
number is incremented on every message, and rolls over to zero, once it hits 255. The same
sequence number is returned by the device-side. It allows the host-side to know which response a
received message applies to.
The next byte is a one-byte command code, followed by the appropriate number of data bytes for
that command.
The final byte of the packet, after any required payload, is a one-byte checksum. This checksum is
the 8-bit sum of the bytes starting with the first byte of the payload length field, through the end of
any payload data.
Every command returns a response.
All the change mute value/status commands will be blocked if the external mute input line to the
box is in the active state. The error response to the command will be returned in that case.
Once a connection has been made to the device, if the device doesn’t receive a message for thirty
seconds, it will timeout and close the connection. A new connection to the device would then have
to be opened.
The GET SYSTEM STATUS message is the recommended choice for the “keep-alive” message.
The system communicates on ports 50000 through 50009.
Commands
1.
INVALID COMMAND RESPONSE
Command code: 0x02
Description: returned if the device receives a command with an unrecognized command code
Input parameters – never sent by host - response only
FLX-E sent data
Byte 0 = 0x1E
start of message character
