Advances in Data Logger Power and CapabilitiesPublished in Pollution Equipment News, September 2007 Written by Michael Fleming, Chief Engineer, Stevens Water Monitoring Systems Technological advancements combined with cost reduction in memory chips, communication interfaces and micro processors have sparked new innovations in the performance and speed of data acquisition platforms (data loggers). With data loggers now able to store up to 8 gigabytes of information, such as Stevens Water Monitoring Systems’ DataLogic 3000, new data loggers are now able to store over 500 million data points. Higher data memory capacity opens the opportunities for extensive data collection and processing - including a growing interesting in recording automated image and video processing. Nonvolatile memory being designed into current data loggers protects the collected data in two important ways. First, in the event of a power failure to the data acquisition system, no collected data or programming is lost. Second, the data logger’s storage is a source of data redundancy for real-time monitoring systems. Nonvolatile memory packaged with increasing memory capacity virtually eliminates the need of purging historical logged data in order to make room for current data measurements. User interfaces with data loggers is also improving with expandable and removable logged data using SD cards (the same technology used in digital cameras, PDAs and PCs); with GUI interface via PC or PDA application software or LCD touch screen displays build into the data logger; with high speed USB connections; with wireless connection using Bluetooth and Zigbee technology; and with fully enabled Internet features including Ethernet options. . Many new data loggers support Modbus and TCP protocols, enabling communication with third-party software drivers and SCADA packages. The central processing unit that controls a data logger’s operations continues to see significant advancements. Many refer to this as Moore’s Law – “the number of transistors on an integrated circuit doubles every 24 months”. Today, more data loggers are being design with 32-bit microprocessors and multiple microprocessors for enhanced operations, flexibility, processing speed and performances. Greater bandwidth in newer data loggers is reducing the need to having data loggers designed and configured for specific applications. As the component size and cost of such advancements continues to decline, new high-powered data loggers are being designed in compact configuration at a reasonable price. Advances in data loggers’ capacity and processing power make them more flexible in accepting a variety of signal types on multiple I/O channels, and is making it easier to mix and match many devices for a variety of application. With more research and development, coupled with on-going technological advancements, the data loggers of the future are sure to have even more diverse functions and storage capacity. Understanding Microprocessors, Advantages of 32-bit CPUs and DSPs A microprocessor chip-- also known as a central processing unit (CPU) -- is a complete computation engine of computers, embedded systems or other electronic devices. A chip is also called an integrated circuit, which can contain millions of transistors. A microprocessor executes a collection of machine instructions that tell the processor what to do. Based on the instructions, a microprocessor does three basic things:
More important than knowing how a microprocessor works is knowing about a microprocessor's power and speed. The Microprocessor's Power The power of a microprocessor is measured in bits. The more bits, the more information (data) the microprocessor is capable of bandying about and, therefore, the more powerful the microprocessor. Specifically, an 8-bit CPU can add/subtract/multiply/etc. two 8-bit numbers, while a 32-bit ALU can manipulate 32-bit numbers. An 8-bit arithmetic logic unit (ALU) would have to execute four instructions to add two 32-bit numbers, while a 32-bit ALU can do it in one instruction. In a way, the number of bits can be compared to lanes on a freeway: If you have only two lanes, too many cars congest traffic, and things slow down. A six-lane freeway, however, has plenty of room for lots of cars, and traffic flows smoothly. With more bits, just as with more lanes on a freeway, the microprocessor can do more powerful programming, operations and processes. Microprocessor Speed Technically, microprocessor speed is measured in hertz, or cycles per second. Microprocessors are capable of doing billions of things in one second. Therefore, their speed is measured in gigahertz (GHz). A microprocessor that can do 1 billion things per second is rated at 1.0 GHz. A microprocessor that can do 3.66 billion things per second is rated at 3.66 GHz. This rate is much faster than 1.0 GHz. The higher the speed value, the faster the chip. And, naturally, the faster the chip, the more you can do in a given amount of time. Trends The trend in processor design has primarily been toward full 32-bit ALU with fast floating point processors built in and pipelined execution with multiple instruction streams. The ARM architecture (previously, the Advanced RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in a number of embedded designs. Because of their power saving features, ARM CPUs are dominant in the electronics market where low power consumption is a critical design goal. Today, the ARM family accounts for over 75% of all 32-bit embedded CPUs, making it one of the most prolific 32-bit architectures in the world. Digital Signal Processor (DSP) In many applications, general-purpose microprocessors (such as the 32-bit ARM) and a digital signal processor (DSP) have distinct roles. The microprocessor and memory take care of mathematical operations, housekeeping tasks for communications with host and interface with other peripherals. The DSP receives input signals and performs tasks that enhance the performance and quality of the system and data such as reflective phase analysis, filtering, noise reduction, modulation, demodulation, encryption, decoding and encoding. A DSP is a specialized microprocessor designed specifically for digital signal processing, generally in real-time computing. These process signals are generally purpose-designed application-specific integrated circuits (ASICs). When flexibility and rapid development are important at high volume, DSP algorithms may also be implemented using field-programmable gate arrays (FPGAs). Since many applications require rapid processing and feedback, engineers often choose DSPs for their speed. Relevant real-time applications that benefit from DSPs include weather forecasting, flood warning, digital image processing, digital communications, data acquisition, control and industrial processes. Summary Companies such as Intel, Motorola, IBM, ARM Limited, and Microchip Inc. have made significant advancements in data processing and control technology in developing microprocessors to optimize the speed and power of electronic devices to meet current and anticipated applications in the future. Stevens new DL3000 has been designed with these latest developments for a powerful data acquisition / control system. |
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