YSIBinaryFormat

YSI 6-series Binary file format (.dat)

YSI do not provide details on the format of the binary files retrieved from their 6-series instruments. This page details my attempts to reverse engineer the file format. This information is based on a file retrieved from a 6600 V2.4 instrument.

Available Sensors for this instrument : -Temperature, -Conductivity, -Dissolved Oxygen (ROX Optical), -pH, -ORP, -Depth (shallow, medium, deep, shallow vented). -Four total optical sensors (ROX Optical DO, Turbidity, Chlorophyll, Rhodamine WT, BGA-PC, or BGA-PE).

The file consists of a header, followed by a variable number of records.

Header

NOTE: The following description is an assumption which is based on a single sample data file; this description may be rendered obsolete when I receive more data files to play with.

The header begins with 111 bytes; I am not sure what these bytes contain - there doesn't seem to be anything useful.

This section is followed by a list of the elements contained in the records which follow the header. Time is always the first element in each record, and is always present. Each entry in the list is 15 bytes, and begins with 0x42. The fourth byte indicates the element type, as listed below. All other bytes in these 15 byte fields are 0.

ID	Field
N/A	Time (Seconds since 1 March 1984 00:00:00)
0x01	Temperature (Degrees Celsius)
0x04	Cond (mS/cm)
0x06	SpCond (mS/cm)
0x0A	Total Dissolved Solids (g/L)
0x0C	Salinity (ppt)
0x12	pH
0x13	Oxidation Reduction Potential (mV)
0x16	Depth (m)
0x18	BP (psi)
0x1C	Battery (V)
0xC1	Chlorophyll (ug/L)
0xC2	Chlorophyll RFU
0xC4	Latitude
0xC5	Longitude
0xCB	Turbidity (NTU)
0xD3	Dissolved Oxygen (% saturation)
0xD4	Dissolved Oxygen (mg/L) from previous value

Record

NOTE This description is specific to the single data file I have at my disposal; this description will likely change when I acquire more files.

Each record is (N+1)*4 + 1 bytes in length, where N is the number of elements in each record (as defined in the header). The contents of each record is identical. Each element is a floating point value, except for time, which is a 32 bit unsigned integer. Each record starts with a synchronisation byte of 0x44. Time is always the first element in each record. All multi-byte fields are stored least significant byte first.

Offset	Length	Description	Type	Note
0	1	Sync byte	uint8	0x44
1	4	Time	uint32	Seconds since 1 March 1984 00:00:00
5	2	Temperature	float	Degrees Celsius
8	2	Cond	float	mS/cm
10	2	SpCond	float	mS/cm
14	2	TDS	float	g/L
16	2	Salinity	float	ppt
22	2	pH	float
23	2	ORP	float	mV
26	2	Depth	float	m
28	2	BP	float	psi
32	2	Battery	float	V
197	2	Chlorophyll	float	ug/L
198	2	Chlorophyll	float	RFU
200	2	Latitude	float
201	2	Longitude	float
207	2	Turbidity	float	NTU+
215	2	ODO	float	%
216	2	ODO Conc	float	mg/L