Coping with Diversity
Even though DAQ systems have gone to paperless, videographic, digital and even wireless, and many of their tasks are split up and taken over by other types of devices, end users can find the right solution by staying focused on the signal they need and then choosing the most appropriate course for it to take.
“There are several physical paths through PLCs, RTUs, fieldbuses, Ethernet and wireless, but there are only three main types of data: real-time for process conditions; late or non-real-time via polling and SCADA systems; and manually entered. All of them can be historized to produce reports for production planning,” says Steve Garbrecht, Wonderware’s infrastructure and platform products manager. “From our perspective, the big news now is OPC Unified Architecture (OPC-UA), which allows DAQs to gather all their data in a consistent manner and a common language format regardless of the hardware used.”
Smaller, more varied applications are also finding they can use DAQ because their data storage capabilities have grown exponentially in recent years. “We’ve gone from floppy disks to costly PCMCIA cards to smart media, Flash cards, USB drives and now secured digital (SD) cards that can hold 2 to 4 gigabytes,” says Pat Cashwell, ABB’s field instrumentation VP. “DAQs used to reach their data storage capacity in a few days or weeks, but now they may not reach it for the lifetime of the device. All of these advances allow DAQ systems that don’t need batteries, are far less temperature sensitive and much more reliable, and make it easier for users to analyze their trends.”
For example, ABB’s Screen Master is a field-mountable, video-enabled DAQ that can send emails and has an embedded web server which allows users to dial in, log on to the recorder and see live versions of all its displays and logs. Its file transfer protocol (FTP) and scheduler also lets users define when and what reports will be sent back to them.
Faster and larger data storage also helps end-users meet specification requirements and documentation rules in their increasingly regulated applications. “The FDA is asking more manufacturers to adhere to its PAT specifications, which means they have to do more validation on their recipes and batches,” says Mike Triassi, marketing director for Optimation, a system integrator in Rochester, N.Y. “Securing testing sample data to prove that a final product matches defined specs is outside the typical control system’s usual capabilities, but DAQ systems can help because they’ve been used in the past to provide similar data on product condition and equipment health.”
Accelerating data speed also is enabling many newer DAQ applications, according to Betts. “One new PC bus standard, PCI Express, runs at 4 Gbps, and has 60 times the bandwidth as PCI bus, which ran at 13 Mbps just two years ago,” says Betts. “Also, where people recently did DAQ with PCI plug-in boards with their PCs, they now can use USB-based I/O and networking. This eliminates many former barriers and lets more users monitor signals such as temperature and vibration that they couldn’t do before.”
Likewise, Mark Albert of Logic Beach says one of his users at a municipal wastewater facility employs Logic Beach’s DAQ system to back up his SCADA system. “So if the network goes down and they lose a day’s worth of data, then they can get it from the logger,” he says. “DAQs can also help with regulatory compliance because some, like our IntelliLogger, can automatically email data to an FTP site or to whomever else is supposed to get it.”
In fact, when the New York/New Jersey Port Authority was running added subway trains in the wake of 9/11, it used Logic Beach’s DAQ equipment to monitor its increased, system-wide electrical current usage more closely. “We programmed our data loggers to collect current demand data seven times per second for four hours during each morning and afternoon rush hour,” says Albert, “and this helped the Metropolitan Transit Authority’s engineers better understand and manage their additional current draw.”
|FIGURE 3: CAREFUL COOKING|
|Quadrant Engineered Plastics uses 20 thermocouples and a DAQ system to keep its ovens from overcooking costly plastic batches, saving thousdands of dollars.
Similarly, Greg Richards, controls engineers and maintenance manager at Quadrant Engineered Plastic Products in Reading Pa., says his company used to have costly overruns in its 30-day production process because Amp readings from its heaters didn’t indicate soon enough when a product run was starting to get overcooked and go bad, which could destroy $70,000 worth of high-grade plastic. Quadrant’s engineers previously used chart recorders and would simply take an oven offline if a problem occurred, but this would sacrifice even more time.
“We recently put 20 permanent-mount Omega thermocouples on one oven and routed their data back to a Siemens NS7-317 PLC, which send it via Ethernet to our Siemens Win CC SCADA computer, where it can be viewed historically,” says Richards. “This gives us real-time profiling and lets us ramp up or down as needed and save far more plastic. We now have this DAQ system on four ovens, and we’re going to add it to 10 more.”
Alvey add that these types of DAQ-based gains are especially possible if engineers work with their IT departments. “When a big company tells me they want to install or update their DAQ system because their end users need data, I tell them to get IT involved from the get go because whatever operating system they’re on, they’ll need IT to help determine what platforms are available at particular levels, what type of data exchange they need, and if they should dynamically update their data,” says Alvey.
Hardware can say how much material or product you’ve got and what condition it’s in, but then you have to decide where to put that data, and for that you have to involve the IT guys. You just need to be flexible and cooperative from the start.
“My philosophy is to give information to everybody in a company because every operation is trying to run ‘lean and mean.’ Having real-time data means what you have to do is right there in front of you all the time, and so there’s a real trend away from having production meetings. DAQ is helping that trend because it meets those real-time goals and targets.
“You also need to decide if your DAQ system is going to be just DAQ or DAQ and control. If it’s both, then you also have to decide who will have control, whether there’s Internet access, what are the operating and tuning parameters, and then security becomes a bigger issue as well. If you don’t need control with DAQ, then don’t do it because you can open a whole other hornet’s nest. Just leave the control local if you can and don’t put it through the web either if you can avoid it.”
However, Cashwell says DAQ’s move into control is probably inevitable. “DAQs can take on so many DCS capabilities that they’re almost like DCSs now,” adds Cashwell. “In the future, I think we’re going to see a lot more blending of DAQs and DCSs. As even more computing power and data storage is added, the next logical step is for DAQs to add more control functions.”