When you have hundreds of different data acquisition (DAQ) devices with a variety of bus options, it can be difficult to choose the right bus for your application needs. Each bus has different advantages, such as throughput, latency, portability, or distance from the host. This white paper explores the most common PC bus selections and outlines the technical considerations when choosing the right bus for your measurement application. 5 questions to help you choose the right bus 1. How much data is going through the bus? 2. What are my requirements for single point I/O? 3. Do I need to sync multiple devices? 4. What are the system requirements for portability? 5. How much more does my computer get from my measurement objects? Other topics 1. Common bus selection guide 2.DAQ bus overview The amount of data that all PC buses can transmit in a given amount of time is limited. This is the bus bandwidth, often expressed in megabytes per second (MB/s). If dynamic waveform measurements are important to your application, be sure to consider using a bus with sufficient bandwidth. Depending on the bus you choose, the total bandwidth can be shared between multiple devices or only dedicated to certain devices. For example, the theoretical bandwidth of the PCI bus is 132 MB/s, and all PCI boards in the computer share bandwidth. Gigabit Ethernet provides 125 MB/s of bandwidth, and devices on a subnet or network share bandwidth. Buses that provide dedicated bandwidth, such as PCI Express and PXI Express, provide maximum data throughput on each device. When performing waveform measurements, the sample rate and resolution need to be set based on the speed at which the signal changes. You can record the number of bytes per sample (rounded to the next byte), multiply by the sample rate, and multiply by the number of channels to calculate the minimum bandwidth required. For example, a 16-bit device (2 bytes) samples at 4 MS/s and the total bandwidth on the four channels is Your bus bandwidth needs to be able to support the speed of data acquisition. It should be noted that the actual system bandwidth is lower than the theoretical bus limit. The actual observed bandwidth depends on the number of devices in the system and the extra bus load. If you need to transfer large amounts of data over many channels, bandwidth is the most important consideration when choosing a DAQ bus. Applications that require a single point of reading and writing often rely on I/O values ​​that require immediate and continuous updates. Due to the different ways in which the bus architecture is implemented in hardware and software, the requirements for single-point I/O may be the deciding factor in your choice of bus. The bus delay is the response time of the I/O. It is the time delay between calling the driver software function and updating the actual hardware value of the I/O. Depending on the bus you choose, the delay can range from less than a microsecond to tens of milliseconds. For example, in a proportional-integral-derivative (PID) control system, bus delay can directly affect the fastest speed of the control loop. Another important factor in single-point I/O applications is determinism, which is the measure of the continuity with which I/O can complete measurements on time. When communicating with I/O, buses with the same latency are more deterministic than buses with different responses. Determinism is important for control applications because it directly affects the stability of the control loop. The design expectation of many control algorithms is that the control loop is always executed at a constant rate. Any deviation in the expected rate will reduce the effectiveness and stability of the overall control system. Therefore, when implementing closed-loop control applications, high-latency, poorly-determined buses such as wireless, Ethernet, or USB should be avoided. Software plays an important role in the latency and certainty of the bus. The bus and software drivers that support the real-time operating system provide the best determinism and therefore give you the highest performance. In general, internal buses such as PCI Express and PXI Express are better than external buses such as USB or wireless for low-latency single-point I/O applications. The Smart Screen Protector Cutting Machine can help stores reduce the inventory of Screen Protectors. It is mainly used to cut Screen Protectors such as Mobile Phone Screen Protectors, Watch Screen Protectors, Tablet Screen Protectors, Pad Screen Protectors, and personalized fashion Back Films. It is very suitable for personal business or shop drainage. Screen Protector Cutting Machine,Protective Film Cutting Machine,Back Sticker Cutting Machine,Phone Sticker Cutting Machine, Film Cutting Machine Shenzhen Jianjiantong Technology Co., Ltd. , https://www.jjtphonesticker.com
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