It's already common knowledge that faster, cheaper, smaller and more powerful microprocessors can let almost any device do data acquisition (DAQ). What's less well-known is this flexibility and affordability lets developers and users scatter chips and DAQ into components and applications that seem to be multiplying exponentially in number and diversity. So, not only do suppliers need to keep up with DAQ's shifting definitions, but they must also try to keep pace with all the new places where DAQ functions can be applied.
"We define a DAQ device as having three main points: 1) an interface to a real-world sensor; 2) a way to convert sensor information to digital format, process the information and store it; and 3) an interface to retrieve the data from the device," says Kurt Wadowick, I/O specialist at Beckhoff Automation. "Anything else the device boasts is just bells and whistles or specsmanship. Trends we're seeing in data acquisition technology include the need for very fast, microsecond-level data collection speeds, and DAQ devices that must be able to interface to hundreds of signal types, store vast amounts of data being generated by ultra-high-speed DAQ functions, and trend data collected to make sure we're gathering it correctly. DAQ components must also have small form factors, be low-cost, have simple-to-assemble parts, and have software that's simple to configure."
In fact, even the struggle that used to exist between simple, slow, standalone, usually remote data loggers and DAQ devices that typically worked with PCs has given way to demands from users, who now want DAQ applications that can work with their iPhones and iPads. "The introduction of USB 2.0 about 10 years ago gave laptops the speed to do DAQ, and allowed our industry to expand," says Peter Anderson, general manager of Measurement Computing (MCC), a subsidiary of National Instruments. "Now our sandbox is all about adopting lower-cost technologies to cut expenses. So we have DAQ systems-on-a-chip with 3.3 V of computing that use less than 5 V in all and A/D converting-on-a-chip, too. As a result, we've shaved 25% off the costs of our designs, and come out with DAQ boards that are twice as fast and twice as capable, while maintaining the same resolution and price."
Despite all of their new forms and flavors, some suppliers say DAQ still should be performed primarily by durable hardware devices that can measure low-level signals in harsh and electrically noisy settings, use an A/D converter, and then deliver data up to PC-based environments. "You can buy any cheap DAQ unit for a nice, quiet lab environment, but many of them have limited voltage ranges, little tolerance for over-voltage, and can't be used in noisy, industrial environments," says Steve Byrom, product manager for DAQ at Yokogawa of America. For instance, Yokogawa's DAQstations have their own secure reporting software, but then transfer real-time data via OPC servers and client programs to higher-level devices, such as SCADA/HMI software, DCSs and historians.
Because so much DAQ used to be performed by proprietary black boxes, they also required many different, specialized device drivers, which further limited their flexibility and applicability. "So many DAQ suppliers began adopting OPC-UA networking, which has become very pervasive because it's wide open and able to play nicely," says Jack Wilkins, sales director at Canary Labs. "They were slower to adopt the more recent OPC-UA for data acquisition, but it's more secure now, too. As a result, DAQ devices are learning to access web servers and sensors, go outside their usual applications and facilities, and serve in more harsh and remote settings."
Canary Labs recently worked with WingTip and Kepware Technologies to develop the hBox, a single-board DAQ module and historian that runs on a wireless mesh network, and can capture many parameters but still be located on or right next to the equipment and applications it's monitoring.
In addition, more powerful microprocessors enable DAQ systems to be configured to handle data from many channels simultaneously, use digital signal processing (DSP) to synchronize incoming streams to phase align data, and employ more math to clean noisy data and capture more useful relationships. "The cost of electronics and data processing is going down, and so the cost of getting good-quality signals for DAQ is going down, too," says Ian Lewis, president of Microstar Laboratories. "For example, our Rotating Machinery Analysis module takes time-domain samples from a rotary encoder, and shows both frequency and rotation data streams to tell us about the vibration issues, motor conditions and help perform engine analyses. We're also excited to be working on a technique to take data samples at any arbitrary rate without requiring aliasing, and use the DSP package in our new data acquisition processor to go from raw to useful data at millions of samples per second."
Because it makes the software bridges that move process data to the HMI/SCADA level, Kepware has seen DAQ's evolution from using proprietary drivers to standardized, open communications. "We've always handled real-time data, but once it's stored, there must be a way to reuse it. So we're making the transition to adding historical data access (HDA) to our KepServerEX platform, which will allow it to read backlogs of data, and push it up through an HDA interface via OPC," says Tony Paine, Kepware's president and CEO. "However, users don't want us to make their PCs and components push this data, and so this requires our software to act the slave end/device end. Providing access to both real-time and historical data allows users to compare performance and see if something is amiss, and see if their larger manufacturing environment is affecting production."
Likewise, though it's known more for sensors and distributed I/O equipment, Turck reports it's adding DAQ capabilities to some of its components to simplify setup and commissioning for users, and bring distributed I/O signals up to the PLC level more easily. "As decentralized intelligence methods offload data processing to lower-level devices, such as distributed, programmable I/O, they can also be set to collect and store data over longer periods just like traditional DAQ equipment," says Randy Durick, director of Turck's network and interface division.