Channel information

Data delivered to the client is always in a raw binary format. To get information about the sample data type, scaling and other important parameters of every channel, the client should send the »LISTUSEDCHS« command. The response contains the following information for each channel, separated by a tab character.

Data	Description	Data type
Ch	Fixed string
Channel type/Index	Channel type or index	Number
Number	Consequent channel number	Integer number
Name	Channel name	Text
Description	Channel description	Text
Unit	Measure unit	Text
Control channel	Is this a control channel	Boolean (1 or 0)
Samplerate divider	Divider for sync channel, »Async« for async channels, »SingleValue« for single value channels	Text Integer/Text
Expected async rate	Expected rate for async channels in Hz	Float number
Measurement type	Defines channel meaning	Integer number
Sample data type	0 – 8 bit unsigned integer 1 – 8 bit signed integer 2 – 16 bit unsigned integer 3 - 16 bit unsigned integer 4 - 32 bit signed integer 5 – Single floating point 6 – 64 bit signed integer 7 – Double floating point 8 – 32 bit unsigned integer 9 – Complex single floating point 10 – Complex double floating point 11 – Text 12 – Binary 13 – CAN message	Integer number
Buffer size	Buffer size for data	Integer
Custom scale	Custom scale after amplifier	Float number
Custom offset	Custom offset after amplifier	Float number
Scale raw data	Scale for raw data	Float number
Offset raw data	Offset for raw data	Float number
Description	Channel slot	Text
Settings	Channel settings	Text
Range min	Range max	Float number
Range max	Range max	Float number
Overload	Can overload	OvlYes/OvlNo
AutoZero	Is auto zero enabled	Boolean (1 or 0)
Channel Tags	Channel tag	Text
DiscreteListCount	Number of items in discrete list	Integer number
DiscreteList Item (0)	Discrete list entry	Text
	Discrete list entry	Text
	Discrete list entry	Text
	Discrete list entry	Text
DiscreteList Item (Count – 1)	Discrete list entry	Text
CurrentMin	Current minimum value	Float number
CurrentMax	Current maximum value	Float number
CurrentAve	Current average value	Float number

To get a real scaled value in the case of non-linear scaling, the client has to apply the following formula:

ScaledValue = ScaleRawData * RawValue + OffsetRawData

Channels in data packets are delivered in the same order as they are listed in »PREPARE TRANSFER« command.

Binary data format

Offset	Length	Data type	Description	Comment
0	8		Start packet string	0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07
8	4	Integer 32 bit	Packet size	Size in bytes without stop and start string
12	4	Integer 32 bit	Packet type	Always 0 for data packets
16	4	Integer 32 bit	Samples in packet	Always 0 for data packets ch.
20	8	Integer 64 bit	Samples acquired so far
28	8	Double floating point	Absolute/relative time	Number of days since 12/30/1899 Number of days since start of acq.

Off = 36 bytes,

Repeat for each channel

If Channel is asynchronous

Offset (bytes)	Length (bytes)	Data type	Description	Comment
Off	4	4	Number of samples	= x
Off + 4	X * SampleSize	Sample data type	Data samples
Off + 4 + X * SampleSize	X * 8	Double floating point	Timestamp samples	Timestamps for samples in samples since start of acquisition

Off = Off + 4 + X * (SampleSize + 8)

If Channel is synchronous

Offset (bytes)	Length (bytes)	Data type	Description	Comment
Off	4	4	Number of samples	= X = SamplesInPacket div Channel SR divider
Off + 4	X * SampleSize	Sample data type	Data samples	Off = Off + 4 + X * SampleSize

If Channel is single value

Offset (bytes)	Length (bytes)	Data type	Description	Comment
Off	4	4	Number of samples	= X = SamplesInPacket div Channel SR divider
Off + 4	8	Double floating point	Data samples	Off = Off + 12

End repeat

Offset	Length	Data type	Description	Comment
0	8		Start packet string	0x07 0x06 0x05 0x04 0x03 0x02 0x01 0x00