Ocean Optics NeoFox Engineering Note - Manual (Page 27)

NeoFox Communication Interfaces
013-20000-010-04-201211 27
Data Copy Settings
By default, the NeoFox’s “data dump” structure is big, and many host devices cannot handle a data stream of
around 60,000 KBps. Therefore, settings have been developed that allow the user to reduce the size and
frequency of the NeoFox’s data dump.
Specifically, there are two features which have been added:
• Data Copy Mode
• Data Copy Type
To understand what these features do, it is important to understand how the Neofox samples and transmits its
data. By default, the process is as follows:
1. A sample is ready
Note: Every 100 ms, the controller calculates a new value of Tau, oxygen, and temperature. Internally,
the actual sample update occurs whether or not the device is currently in the process of transmitting a
previous sample.
2. Data is copied into the transmission buffer.
Note: If the device is not currently in the process of transmitting a previous sample, it copies its “data
dump” of its parameters to the transmission buffer. If the device is currently transmitting, then data will
not be copied until the transmission is complete. If a new sample becomes available before the current
sample has begun transmitting, then the current sample is never transmitted and the new sample will
take its place waiting for the end of the previous transmission.
3. Once data has been copied into the transmission buffer, it is immediately sent to the host via the UART
Note: This can be over RS232 or the USB, depending on which mode is currently selected.
Data Copy Mode
The Data Copy Mode setting allows you to determine when data should be copied into the transmission buffer.
There are two options for this parameter:
• Auto – When the auto mode is enabled, the default behavior will occur, as listed above.
• Request – When the Request mode is enabled, the device will look at the current value of the Data Copy
Trigger setting to determine whether or not to perform the sample copy. When the Data Copy Trigger value
is 0, it will not perform this copy. When the value is 1, it will perform the copy and set the value of the Data
Copy Trigger parameter to 0; it does not perform another copy until you request it to do so.
Data Copy Type
The Data Copy Type parameter can be used to reduce the size of the data dump. There are currently three data
types available to users:
• Type 1: The original data structure format, as documented earlier in this document.
• Type 2: The original data structure format, as documented earlier in this document, but without the two
waveform structures included at the end of the structure. Therefore, the length of the structure is 932 bytes,
and the Protocol Rev byte will be equal to 0x02.
• Type 3: A measurement only structure, which includes a very small subset of the information available in
type 1; specifically, it only includes measurement data.