Although the IL-Mini is equipped with a maximum of 4 analog inputs and one digital input, the IL-Mini can be purchased with a Modbus RTU Master option. This allows the unit to communicate with one or more serially connected transducers on a single Modbus RS-485 twisted pair cable leaving the four analog channels available for conventional thermocouple, Vdc or 4-20mA type inputs (eg pressure). With this expanded capability, it is possible to perform Supply Side audits on one, two and possibly three compressor installations… simultaneously!

In a Modbus enabled IL-Mini Compressed Air Audit system, the compressor electrical transducers and the air flow transducers can be provided with Modbus interface which then allows for up to four 4-20mA pressure transducers to be connected to the remaining analog inputs.

For the compressor electrical measurements, utilize the Modbus interface WNC family or the PS3-D electrical meter transducers. With the Modbus interface, each meter is assigned a Modbus network address and a pair of wires is daisy-chained between the meters. The IL-Mini Program Net is then constructed to read the desired electrical parameters from each of the power meters.

In addition to the increased channel capability offered by Modbus, one other major benefit of using the Modbus enabled WNC or PS3-D meters is that a multitude of electrical parameters can be read and logged from the Modbus connected meters… including phase voltages, phase currents, power factor, kW (demand), kWh (energy), VAR and more. This data can be valuable in assessing the compressor health in addition to the energy consumption critical for audits.

The CDI line of air flow meters is available with Modbus interface as an alternate to the analog 4-20mA output. Multiple Modbus enabled flow meters can then be installed on two or more compressor outlets and flow logged to a single IL-Mini.