Such devices can sample temperatures at pre-determined intervals. At the end of the trip, the user can download the information and see where the temperature was throughout the route. "You can print out the information you collected onto a small stand-alone device for review right in the receiving area," explains Leach.
While these types of devices are commonly used, they have their shortcomings. "Recording devices such as chart recorders and digital data loggers are used when data integrity is essential or when manual monitoring is impossible or impractical," says Fettig. "These units store or record data, but they have space limitations, so the data must be gathered before it can be used. This means downloading or copying."
In spite of the need to download information, most providers of temperature monitoring now have sophisticated software to help companies extrapolate information. DeltaTRAK's software, for instance, can help users identify frequent temperature abuse among suppliers, analyze the effects of temperature during transport on shelf life, and can be used as evidence to support insurance claims.
John Young, iButton sales manager at Dallas Semiconductor, says that the cost and equipment needed for downloading information from a logger into a PC is both affordable and easy. "You need only a $35 cable and adapter to read iButtons from a PC," he says. "We also have several partners that make handheld readers."
Another advantage to electronic devices is that they have no moving parts and they're impossible to tamper with. They tend to be more accurate and precise than mechanical devices that at times might produce charts that are difficult to read.
Regardless of the type of monitor used, end users must determine where to place it for the best return of information. "We don't stipulate where customers place their devices," says Young. "But our devices are so small they can be placed just about anywhere."
Fettig says that today most devices are placed in the area'a cooler, freezer or trailer'or among the product load on a few pallets. "The trend for the future will be to track and capture as much information as possible from farm to fork. Some more technology advances will be required before it is practical to track every product on every pallet. Today, it is with wireless and even with digital data loggers that tracking the handling of lots and loads is possible and practical."
While manual and mechanical devices have their place in temperature monitoring, it is real-time monitoring, whether wired or wireless, that is making headlines today. "Real-time information is much more valuable because it is current and can be acted on," says Fettig. "Wired devices have a high upfront cost and lack flexibility. Wireless devices can be placed easily and even more importantly, they can be moved easily or be used on products that move."
Based on active RFID technology, the wireless devices simplify the transmission of information collected by a monitoring device, says DiRubio. "If you're using a basic mechanical/electric device, you have to locate the device, remove it, connect it to a PC and download the information," he says. "With a wireless device, when a trailer backs up, the device is recognized by a network and the information is transferred into a database immediately."
This would be a big boon to a retailer, for instance, who could instantly determine if the data doesn't hold up to standard business rules. The retailer could take instant action, refusing to accept the load if it fell out of standard.
"There are other, more subtle advantages of wireless loggers," says Steve Knuth, president of T&D U.S., in Saratoga Springs, NY, "such as real time monitoring over a distance or in environments where motion is a factor. After all, there can be substantial benefits in being able to determine that a problem is occurring in time to do something about it, rather than finding out about it after the fact, which is what most conventional loggers tell you."
Wireless loggers can transmit any information you would need, such as the availability to store and transmit in many states temperature, humidity and door status. Fettig says that when coupled with a real-time alerting system, potential disasters can be easily avoided.