Loggers Keep Feeding Data-Hungry Users

April 4, 2008
Recorders and DAQs Have Survived the Advent of PCs, Adapted to Cooperate with Software-Based Historians and Continue to Serve in Applications Where Computers Can't Go

By Jim Montague, Executive Editor

Recorders and data acquisition (DAQ) systems are dead! Long live recorders and DAQs!

Technical advances in process control and automation often unfold in unexpected and ironic ways. Software fuels a renaissance in supporting hardware. Wireless needs more cables at the transmitting and receiving ends. PCs increase paper and printing instead of replacing it. You get the idea.

Not surprisingly, DAQs and other data loggers are no exception. These devices were supposed to be overtaken and replaced by any computer with a software-based historian, data collection interface, and reporting and trending functions. There’s no doubt this is happening to some extent. Low-cost computers in all their various forms are taking on data-recording jobs in traditional settings and in locations where recording used to be too costly or inaccessible.

However, while recorders’ and DAQs’ days may seem to be numbered, computer- and software-based logging seem to have merely whetted users’ appetites for data recording, archiving and analysis. Also, many industrial settings remain where computers can’t perform as well as traditional DAQs. So, who gets the call when this happens? You guessed it.

“Users who never had recorders or historians before are adding them now because software allows it. A lot more companies are gathering more information in more applications to help make business decisions,” says Steve Goldberg, industrial systems division director for Matrix Technologies, a CSIA-registered system integrator in Maumee, Ohio. “For example, we work with a steel mill that processes coils, and it’s now able to record, archive and trend fast, millisecond-level data that it couldn’t acquire before to check for quality.”

Ashish Desai, sales engineering supervisor at Omega Engineering Inc., adds that, “Many non-technical people are beginning to use DAQ products, and they have differing levels of expertise. So it’s even more important for us to help them define their expectations for recording and teach them how to use loggers and DAQ systems that will work best for them. For example, we even had one user put 26 inexpensive loggers in a shipment of refurbished PCs being trucked from the East Coast to the West Coast. They previously had problems with equipment suffering heat damage during shipment, and so the loggers helped them monitor temperatures in the truck.”

Real-World Recording

Similarly, making sure that newly drilled oil and gas wells have been properly sealed usually requires trucking a mobile DAQ system between wells to check and document the status of each. After a well is drilled, a steel casing is lowered into it, and cement is pumped in to create a seal between the casing and the rock. Of course, this job means lots of heavy vibration and dust that can play havoc with typical PC-based data collection equipment.

To avoid this problem, one oil and gas logging and perforating company has built a ruggedized DAQ system to do its electronic well surveys, which consist of logging cement quality, gamma radiation, temperature and depth. Rocky Mountain Wireline Service in Grand Junction, Colo., reports it reduced downtime and increased accuracy of its surveys with its home-grown DAQ system that uses National Instruments’ LabWindows/CVI software and PXI/Compact PCI hardware.

“Our traditional DAQ system is rack-mounted in a wireline truck. It must withstand vibration and dust as the truck travels over rough roads, which causes problems for industrial PCs. For example, the RAM chips and A/D cards often vibrate out of position, even with retainer bars and clips holding them in place. These PC maintenance requirements and resulting truck downtimes were a problem. We needed a new system that was reliable and easy to repair or replace,” says Corin Chepko, Rocky Mountain’s owner.

The company’s DAQ system records acoustic cement-bond logs, which determine the quality of the cement between the well casing and surrounding rock. An acoustic bond tool emits a 22-kHz ‘tick’ 20 times per second and measures reflected arrivals of sound for 1,000 microseconds. The acoustic tool is stacked with a gamma ray tool, which emits a pulse when it detects a gamma ray, and a casing collar locater tool that adds a low-frequency component. The signal that comes up from the single conductor wireline is separated into two signals before it enters the A/D boards—one with the low-frequency component of about 10 Hz removed, so the analog trigger pulse remains on a flat baseline, and the other with the low frequency intact. A digital input from an optical encoder calculates the tool depth. When the acoustic tool ticks, a -5 V trigger pulse is sent up the line to indicate the arrival of the sonic signal. Upon detecting the acoustic trigger, the system scans the analog channels at 256 kHz each for just under 0.05 sec (11,800 samples), then transfers the data for processing and rearms the trigger to be ready for the next acoustic trigger.

“We decided to use PXI hardware for our latest upgrade because of its ruggedness and modularity. We’re planning to expand the system’s capabilities in the future, so we chose the PXI-1050 chassis because it has eight PXI slots to accommodate our application, as well as four SCXI slots for signal conditioning if we add more inputs, such as line tension,” adds Chepko. “In the end, upgrading our software for the PXI system was quick and easy, and we can achieve better logging performance with PXI hardware. Upgrading to a PXI DAQ system resulted in valuable time savings, as well as plenty of room to upgrade future system functions. Using LabWindows/CVI made the software transition fast and easy. The new system reduces truck downtimes and computer maintenance, and technicians don’t need to solve problems immediately in the oil field because modules can simply be replaced and fixed at a later time. With the increased accuracy of our hardware, we can deliver a higher-quality cement bond log to our customers and a quicker depth determination with our casing collar logging program.”

Any Path to Useful Data

In fact, it’s not computing and software’s power that’s fueling the DAQ resurgence; it’s actually the never-ending appetite for useful data.

“Users are realizing that information is king. They’re combining critical data from their manufacturing operations with information in their business systems, allowing them to find additional efficiencies in their overall operations. Properly designed data collection systems give the right information at the right time to the right decision makers,” says Brian Beaufeaux, of Industrial Automation Engineering, a CSIA-certified system integrator in Ham Lake, Minn. “Users need to set clear goals of what they’re trying to accomplish with the data they collect. Are they trying to do downtime/efficiency monitoring? Preventative maintenance? Improving mean time between failures (MTBF)? Inventory monitoring? Asset security? Lights out operations? Deciding this will help them focus on the right tools and technologies. There’s lots of data that’s already available in their process control systems. Smart MCCs can feed back pages of data from each bucket. So each situation needs to be evaluated individually. Various tools are a better fit depending on point count density and location, for example. One would use different methods and tools to collect data on their generator health status if it’s in a plant or located in remote lift-station applications.”

Shrinkage Spurs Data Relocation, Capabilities

Just as computers and DAQs become smaller, related A/D and signal conditioning components are shrinking too. As a result, users have to reevaluate whether to store data locally in the module or push it to long-term storage on a laptop PC or server, says Jim Campbell, president of Viewpoint Systems, a CSIA-certified system integrator in Rochester, N.Y. “Smaller computers also mean that users can push added intelligence down to recorders, which means they can log, not just physical parameters, but also simple and even complex events. For example, recorders can now log changes in nominal pressure over a long period, but they also can establish a dead band so the recorder will only log when readings move outside that band. Small, industrial 200 MHz Pentium PCs can be the logger in some cases and can be assigned to log more often when a change happens that the users want to monitor. This can help users secure only the data they want and save power at the same time.

Paper Persists

Though most users are moving from hardware and paper-based recorders to software, many food and pharmaceutical application still require paper records for documentation and regulatory compliance. “Many users want to get away from maintaining paper, but others still must have paper for critical data needed to insure safety. And some users don’t want to record and run their data through a digital system that might lose it,” says Goldberg. “Still, some federal rules, such as 21 CFR Part 11, are allowing greater use of electronic records and signatures, and so more users are investigating and implementing them. If designed properly, a digital DAQ system can be just as secure as paper.” 

Logger To-Do List

Campbell adds there a few important questions users must ask themselves to help select the DAQ system for their application. These include:

  • Is this a temporary monitoring situation, or is it a permanent installation?
  • Is it in a physically tight spot? How small is it and how hard is it to reach? If you can run signal wires to it, how much signal noise is there?
  • Are you logging or archiving data for historical purposes, or are you performing statistical process control?
  • Do you need to perform smart event detection for data compression, or do you need to be able to react to events?
  • What kind of delivery time and funding do you have available?

“Users can understand the business case for collecting data by asking, ‘What data will help us operate more efficiently?’ They can understand how mission-critical the data is by asking, ‘If we lose communication, do we need to store the data in the field device until we re-establish communication?’ ” adds Beaufeaux. “Next, they need to decide who needs the data, how often and in what format because there are different needs for the plant manager and the CEO.

“They also need to phase in the project because it will allow them to ‘eat the elephant one bite at a time,’ as well as take advantage of newer technologies that become available. For example, our group of companies installed a nationwide DAQ system for a railroad client that provides real-time usage and inventory monitoring of its diesel fuel storage facilities, which use more than 1.4 billion gallons of fuel per year, and we’re continuing to provide data-reliability services. Finally, most users budget for the initial capital expense, but they also need to plan for ongoing operational expenses associated with maintaining their DAQ system.”

Coming Attractions

“The cost per point to collect data will continue to decrease due to advances in Ethernet, mesh networking, RF, cellular and satellite technologies,” adds Beaufeaux. “As it becomes more cost-effective to collect data, it will become even more important to understand how to use it and not be overwhelmed. Being able to analyze the data and report the findings in a concise and timely manner to stakeholders will allow them to make better, more informed decisions that directly impact their bottom lines. There are new collaborative and score boarding software tools that help companies truly reap the value from their data.” 

Four Forces in Recorders and DAQs

Jim Campbell, president of Viewpoint Systems, a CSIA-certified system integrator in Rochester, N.Y., says there four main trends affecting recorders and DAQs in process control applications and markets over the past several years.

  • Unusual Accessibility—Increasing demand for data recording in hard-to-reach areas, where users just want to put small DAQ device. Users don’t necessarily need to connect these devices to an overall network and reportedly are often willing to come back, and extract data later.
  • Going Mobile—More mobile data loggers are being used on moving vehicles, such as freight trucks, autos on proving grounds and railroad cars. These reportedly are mainly black-box recorders in settings that can’t have a hard-wired connection. Many of these also are reporting stored data via wireless protocols.
  • MES and ERP Connections—Recorders are working more closely with historian capabilities in manufacturing execution systems (MES) and enterprise resource planning (ERP) software. Not only are DAQs retrieving values for MES and ERP systems, but also loggers are actually being made part of these systems.
  • Smaller and Less Costly—Form factors of many DAQs are getting smaller, and this is driving down their costs. Ethernet and USB-based features are growing in popularity, and this reducing the costs of some recorder components.