Upgrading Instrument Panels Economically and Effectively To Provide Data Logging and Remote Communication

Written by Graeme Murphy – Product Manager TechRentals and Paul Brooker – Consultant, TechRentals July 2012

There is sometimes a need to add local data logging and remote data transmission to an existing instrumentation system. A TechRentals customer was recently faced with this task for a 50 year old instrumentation panel. While a complete replacement might have been justified in some cases there will be circumstances where a plant is near to the end of its life. There are also issues such as operator familiarity and retraining.

In the case of this particular application, what was needed was to monitor an operator panel which was built before the days of data loggers. The instrument panel was old and its scaling was not known. However all display instruments were 4-20mA. The engineers required measurements from the panel to be logged and to be able to monitor these remotely. They had encountered some intermittent plant or measurement problems.

A Fluke 744 calibrator was used to check the scaling and a Datataker DT80M was used to subsequently record, display & transmit values from the panel.

Instrument scaling and their internal shunt resistors were determined using a Fluke 744 calibrator set to 4mA and 20mA. The data logging solution was to be based on measuring the voltages developed across these existing shunt resistors. This was to avoid breaking the loop or having additional resistors in the network. The shunts ranged from 100 to 2,500 ohms which in the case of the 100 ohm resistor meant that the voltage range was quite low being from 0.04 to 0.2V.

The data logger selected was the Datataker DT80M which having a differential input and an appropriate sampling rate is capable of making accurate measurements in an industrial environment. It is also readily configured to connect to the mobile phone network. It has both automatic and alarm triggered data transmission capabilities enabling data to be automatically emailed to multiple addresses. SMS communication is also possible.

The Datataker DT80M's dEX logger software was configured to display the panel readings appropriately on the Datataker's password protected web interface. The logger was also programmed to send summary data in a CSV file to the appropriate email addresses and a number of alarm conditions were also configured to send SMS messages when different criteria were met. The Datataker's modem auto configured itself and connected to the mobile network. Engineers based at a different location were able to login and observe real time instrumentation panel measurements, and to receive the daily email reports. dEX datalogger software is an intuitive graphical interface that allows remote logger configuration, view of real-time data in mimics, trend charts or tables and retrieval of historical data for analysis.

A 50 year old industrial control panel was now able to be monitored anywhere simply using its IP address and appropriate passwords. Summary reports of the operation were now emailed daily. A simple and economical solution was realised using a Fluke 744 calibrator and a Datataker DT80M data logger.