“How rapidly should I test my input signal?” is a genuinely basic question among DAQ system originators, and particularly those without formal preparing in either DAQ systems or test hypothesis. The straightforward answer is the system must example sufficiently quick to “see” the required changes in input. In an absolute input system, the base required specimen rate is commonly characterized by Nyquist inspecting hypothesis. Nyquist found that to reproduce a waveform, you have to test at any rate twice as quick as the most noteworthy recurrence segment contained in the waveform. For instance, if your input signal contains recurrence segments up to 1 kHz, you will need to test at any rate at 2 kHz, and all the more practically, at 2.5 – 3 kHz.
Likewise with input resolution and precision, there is an inclination among DAQ system fashioners, especially those new to the business, to “overdetermine” the system input test rate. There are not very many applications where it is important to test a thermocouple more than 10 times each second, and most will presumably be satisfactorily served at a tenth that rate. Keep away from the allurement to over-example as it regularly expands system cost, memory necessities, and ensuing examination costs without including any helpful data Note that the above relates for the most part to input just systems. Control systems speak to a totally unique arrangement of contemplations. Not exclusively should the input testing rate be sufficiently high, however, the CPU must have the “torque” to play out the figurines sufficiently quick to keep the system stable and the yield gadgets must have the speed and precision required to accomplish the coveted control comes about. An exchange of control hypothesis is well past the extent of this note, however there we will include a couple notes that might be useful.
To begin with, in the event that you require any kind of deterministic control, and additionally, a hiccup in your control calculation would be dangerous, or your system refresh rate is more than 10 refreshes per second, you will probably need to consider utilizing a constant or “pseudo ongoing” working system. ReadyDAQ offers to bolster for QNX, RT Linux, RTAI Linux, RTX, and XPC. Numerous clients additionally find that however, it is not a completely deterministic constant OS, Linux-based applications have sufficiently low latencies to be utilized as a part of some higher speed control applications.
