What Is A Data Logger? 

Data Loggers have long been used to chart or plot events to build a record for future investigation. Early devices were analogue, often recording directly to paper. With the advent of digital storage it is now more common to see records being stored digitally. 

There are many different types of Data Logger found on equipment as diverse as aircraft (black box recorder) to medical (vaccine storage). Data logging is increasingly being used to monitor energy consumption and to gather manufacturing data from the factory floor.

Types Of Data Logger

Data Loggers are often distinguished by the number of channels they can record. A single point Data Logger can come in the form of a USB Logger with built in temperature sensor. These devices are often used to record temperatures and are widely used in the Cold Chain for monitoring refrigeration. 

Industrial Data Loggers have more channels with different communication options and a larger storage capacity. 

Product Name	IP Rating	Physical Input Channels	Internal Memory	Mounting/Type
TagTemp USB	IP67	1	32K	Portable
LogBox WiFi	IP40	4	140K	Surface Mount
FieldLogger	IP20	16*	512K**	DIN Rail

Figure 1: Novus Automation Data Loggers Basic Product Comparison

*FieldLogger Master can also log remote channels via Modbus.

**FieldLogger internal memory is expandable, other products have fixed memory limitations.

How To Choose A Data Logger

When selecting a Data Logger there are some important questions to ask which can help you to find the right product:

What Power Supply Do I Need? - the Data Logger will require some form of power to operate the internal electronics. For standalone applications you may require a device which will function entirely on a battery. Control systems or off-grid installations may prefer a lower voltage such as 12-24V to power the logger. In many instances the most convenient form of power is a local 230V AC supply. 

How Many Channels Do I Need? - Data Loggers are often distinguished by the number of channels they can record. Conventional logging is based on each channel representing a hardwired input, often in the form of an analogue or digital signal. This could be a temperature sensor, flow meter or standard digital input with a binary state. Many data loggers now offer Universal Inputs which can accept a wide range of industrial signals

How Many Logs Do I Need To Record? - most Loggers are specified based upon their internal memory limit. It is important to calculate the number of data points and sample rate prior to purchasing. This will give you an idea of the number of days the data can be stored before overwriting occurs. A common feature with Data Loggers is circular memory which means that when the storage is full the oldest data begins to be overwritten. It is important to design your system in such a way that the data can be extracted prior to overwriting.

Figure 2: Data Logger Calculation For FieldLogger With 512K Memory

Please note the internal memory limit increases with fewer active channels or a decreased logging frequency. FieldLogger memory is expandable using an SD Card which is a simple method for increasing the logging capacity.

What Communications Do I Need? - for a single channel Data Logger with built in USB there is often only one way to download and view the data. Simply plugging the USB stick into a computer will give you access. For more complex systems it is worth considering the most convenient and reliable method of communicating with the Logger. It is now common for Loggers to be equipped with Ethernet ports, Bluetooth and WiFi functions. This provides greater versatility when it comes to configuring or accessing the logs.

Novus Automation Data Loggers Compared

Single channel USB Loggers - Novus have a range of basic USB loggers suitable for recording temperature. This type of Logger has a built-in battery and the internal memory can not be expanded. They are best for simple applications such as Refrigeration or environmental temperature monitoring. Batteries are replaceable on the TagTemp model which is also IP67 rated.

Basic multichannel Loggers - the LogBox range is best for a limited number of 3-4 channels with hardwired inputs. The main communication method is specified at the time of purchase i.e. Bluetooth or WiFi. The memory is limited at 140K logs but this is often enough for midrange applications. Typically they are used to log instruments such as flow meters (instantaneous and accumulated) or any small but significant part of a larger process. Do to the convenience of WiFi, multiple LogBoxes can often be found in a single building. They are quick to install and commission. When external power is lost the logging process continues until the internal battery expires.

Advanced multichannel Loggers - FieldLogger is the flagship data logger from Novus Automation. It comes with the largest number of channels and features. It also has the largest built-in memory (512K) which is expandable with an SD Card. If your IO count is greater than 4 then the FieldLogger is often the best option. FieldLogger can record signals transmitted by RS485 and can also create it's own virtual channels based upon calculations. Many users opt for the Ethernet model as it allows the device to join a local network which makes commissioning and monitoring simple. Any PC on the network can be used to access the logger with the free FieldLogger Configurator program. FieldLoggers can be found in factories, solar farms, utility monitoring, agriculture and more.

Novus Automation Data Loggers are a great choice as they are reliable, accurate, well specified and come with free software. They are a great solution for non-invasive data logging which operates independently of the process.