Limesoft DCU - Software Data Logger and Controller

Traditionally, PLCs were used in industrial applications to interface instruments, log data and control solenoid valves. Various facilities have their own PLC programming standards that can drive up the costs and programming time. What if you could standardise the controller you use in your analytical package?

Limesoft DCU can interface, acquire and store data from a variety of instruments, devices, sensors, analysers using a variety of Ethernet, Serial, 4-20 mA, or Digital I/O protocols such as Modbus and OPC. It features a powerful RegEx Parser Engine that can be used to read data from devices that implement string-based communication protocols. As a centralised Data Hub or Gateway, DCU can then respond as a Modbus Serial or Ethernet Slave and provide data to one or multiple Modbus Masters. All the data can then be packaged together and passed in a convenient format such as Modbus TCP/IP map. It can function as an OPC Tunneler to avoid complex DCOM layer configuration.

The HMI can display interactive process and mimic diagrams, histograms, charts, and data tables, push buttons to trigger various control tasks or set analog values.

DCU supports complex control logic programming, scripting, and scheduling for tasks such as: energising solenoid valves, validation and calibration sequences, purge, blowback, sample handling, flow, PID (Proportional Integral Derivative Gain) control loops, time-sharing and stream switching, trip point monitoring and condition-based alarms. This can potentially save a lot of time typically spent programming PLCs, as DCU is a software based controller and can be reused for future applications. All control commands can be executed using Windows Task Scheduler, to automatically initiate calibrations, perform blow-back or switch the analyser stream.

Additional diagnostic information can be obtained from analysers to monitor device health status and performance, generate alarms and notifications, trigger preventative maintenance procedures and reduce downtime. The curve fitting algorithm is used to detect when the actual response value during validation has approached the expected set point, calculate the drift, and proceed to the next step. This allows gas cylinders to last longer and saves time.