B&K 4071 user manual Data Formats, Floating Point Format, Example, Rules for Floating Point format

7.8 Data Formats

7.8.1 Floating Point Format

A floating point number consists of a mantissa and an optional exponent. Downloading floating point values is slower because it can take many characters to represent a single numeric value. This format has an advantage, however, because it is so flexible. Many sources of data (BASIC trig functions, spreadsheets, digital oscilloscopes, and waveform design packages) can generate data in this format.

Rules for Floating Point format:

1.The 4071 expects all floating-point values to be between -1.0 and +1.0. If a number falls outside that range, the number is set to -1.0 or +1.0. These correspond to the peak values of the waveform. If the output voltage level were set for 5V p-p, for example, then +1.0 corresponds to +2.5V and -1.0 corresponds to -2.5V (across a 50O load). For maximum signal fidelity, you should design your waveform so that the peak values “just fit” into the range of -1.0 to +1.0. You will then be using the full output range of the DAC.

2.To separate each number, you may use commas, tabs, spaces, carriage returns and/or linefeeds, semicolons,

colons or basically any character that is not among the following: 0 1 2 3 4 5 6 7 8 9

. - + e E X

3.You do not have to include an exponent (i.e. e-5). If no exponent is given, the 4071 assumes that the exponent is 0.

4.Space characters are not allowed between the mantissa and the exponent.

5.Use of the "+" character for positive values is optional.

6.To set the SYNC Out output high during a data point, put a "p" or "P" BEFORE that data point. The "P" character may have space around it if desired. SYNC Out is set low for all data points that do not have a “p” or “P” before them.

Example

A six-point waveform with SYNC Out set high on point #4:

0, .584737, 3457e-4, p .0004857e+3 -.000485 -1.0e-0 X

The “X” character denotes the end of the data and is optional. If the “X” character is missing, the 4071 will assume all data has been sent after 1-second timeout.

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BK Precision 4071 User Manual Rev.2.2