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The text data file format will contain a line of text for each sample. The samples are in

chronological order from oldest to newest. The resulting file will be quite large and will

probably need to be reduced for use in most data analysis programs. Some users may also find

it easier to understand this format than the binary format for use in custom post processing

software. Each line of the text file is formatted as follows.

Where: <Segment> is the memory segment in the range 0 to 31 dependant

on the current memory geometry settings

<Post Trigger> is 0 if the sample was taken before the trigger event

and 1 if the sample was taken after the trigger event

<Channel x> is the absolute value of the sample over the current full

scale range as an offset binary value of 0 to 4096 – that is, with the zero

volt level of input signal plus offset being 2048. This value includes any

effect of the instrument offset settings.

The binary file format contains sequential samples in a six byte equivalent to the line of

text in the text file format. It is written as a data structure from the C programming language and

stored with no padding between samples. Post processing software will need to be aware of this

structure’s format and will generally read data from the file into an equivalent structure to

preserve the byte ordering. The structure is as shown below, assuming the Windows software

conventions that a BYTE is an unsigned 8-bit number and a WORD is an unsigned 16-bit

number. The descriptions of the elements are equivalent to corresponding items in the text

format above.

typedef struct binary_data_record_st

{

BYTE segment;

BYTE trigger_valid;

WORD sample_ch1;

WORD sample_ch2;

} T_BINARY_DATA_RECORD;

Note that these data file formats do not contain any information about the settings of the

instrument from which they were written. Some information about the sample memory

geometry may be inferred, but other potentially important settings information must be recorded

separately if needed. The objective of the Save Data function is to save raw data for post

processing in its simplest possible format. Many post processing programs will require no more

data than this, while still others may require little else. Most will require a knowledge of the

sample rate or other basic points that the user might consider recording in the file name. All will

be affected in complexity and processing time by the size of the data file and anything other than

uniformity in its content. This is the logic behind the simple format given.

DDC TR122 User Manual

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