Case Studies

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Automated Solvent Skid Control with a Schneider Electric Modicon PLC

Posted in Manufacturing Automation and Intelligence, PLC Programming


DMC worked with a client to develop a controls system for an automated solvent skid used to extract plant matter into concentrates. This particular solution was designed for THC extraction from cannabis plants, but can be used for any type of plant. Through close coordination with the client, DMC set up, programmed and commissioned the first automatic prototype of the solvent skid. 


DMC’s client developed a solvent skid system capable of extracting concentrates from plant matter. The original manual process lacked consistency and required constant input from an operator. By automating the process, more product can be produced more efficiently and with less variation between batches. 

Consistency of the product was also improved with the implementation of recipe management and data logging. Stored in a SQL database, the recipes can be set to control the system parameters, including process duration and temperature set points. Recipes can be added, modified or deleted directly on the HMI. Data logging is used to record the system parameters at various intervals through the process. These logs are then emailed to a defined address to ensure consistency between batches and allow for a more rigorous quality control. Email functionality is made possible via the eWon cellular gateway, which provides a 3G network for the system to use. The eWon also allows for the system to be accessed remotely so the process parameters can be viewed in real time from anywhere in the world.

The solvent skid includes two separate subsystems, each controlled by its own Schneider PLC in a master/slave configuration. Since the process requires a very specific operating procedure, it is important that the master is able communicate with the slave, both for monitoring and control. This was accomplished using a Moxa Wireless Bridge. This device sets up a LAN network connection which the PLCs utilize to communicate.

Safety was a great concern because this process involves volatile liquid butane. The system was designed to be Class 1 Div-1 compliant. It includes features such as lower explosive limit (LEL) monitoring and a specific emergency shutdown procedure.

Throughout the project, DMC worked closely with the client to ensure that all functionality and safety requirements were met. In the end, a fully automated solvent skid prototype was ready for further testing and marketing. 

Learn more about DMC's Schneider Electric solutions.

Customer Benefits

  • Automating a process that was previously manual to improve consistency and efficiency
  • Incorporating recipes from SQL database
  • Data logging and emailing
  • Class 1 Div-1 Safety Rating 
  • Remote access via eWON
  • Wireless PLC communications and data connection


  • Schneider Electric SoMachine PLC software
  • Vijeo Citect HMI software
  • SQL Server
  • eWon Cellular Gateway
  • Moxa Wireless Bridge Communications