Why does the Data Acquisition Toolbox “read” function return faster than the specified “span” in MATLAB R2025b?
显示 更早的评论
I am using the "read" function from the Data Acquisition Toolbox in MATLAB R2025b to read data from a device. I want to collect data for 3 seconds. The documentation describes a "span" parameter, which can be specified as a duration. When I call "read(dq, seconds(3))", and I notice the call executes for less than 3 seconds when timed using "tic" and "toc". How is this possible?
采纳的回答
MathWorks Support Team
2026-4-17，0:00
It’s possible for “read” to execute for a time shorter than the specified "span" if the data buffer already has data when “read” is called. The example below illustrates this behavior.
dq = daq("ni");
addinput(dq, "Dev1", "ai0", "Voltage");
start(dq, "continuous");
pause(1);
tic;
data = read(dq, seconds(3));
elapsed = toc();
stop(dq);
dataSpan = seconds(max(data.Time) - min(data.Time));
fprintf("Recorded elapsed time: %.3f s\n", elapsed); % ~2.000 s
fprintf("Data time span: %.3f s\n", dataSpan); % ~3.000 s
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Data Acquisition Toolbox Supported Hardware 的更多信息
2026-4-17，0:00
2026-5-5，15:23
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
