Case Studies

schneider, oil and gas, water treatment, PLC

Centralized System Control with a Schneider Electric Modicon PLC

Posted in Manufacturing Automation and Intelligence, Oil and Gas Engineering, PLC Programming


DMC worked with a Colorado company in the oil and gas industry to simplify their PLC system architecture. DMC helped the customer circumvent defunct control hardware, implement expanded functionality, and add facility-wide safety shutoff capabilities. This modification gives the customer flexibility to pursue further upgrades and reconfigurations to their existing equipment while also improving their current operational capabilities.


DMC’s customer operates an oil and gas wastewater treatment facility. The facility accepts tanker trucks full of dirty water from oil extraction processes. The tanker trucks are offloaded by a set of pumps into a series of common holding tanks before moving through the filtration and separation process.

The customer’s original PLC system made use of a central Schneider M340 PLC in combination with local PLCs at each of their four truck offload pads. The customer is reconfiguring their facility to increase capacity and wished to remove the PLCs at the offload pads. DMC routed control of the offload pumps through the centralized M340 PLC. This allowed the customer to remove the difficult-to-use controls on the truck offload pads and gave them the flexibility to easily add more offload pads in the future.

The customer frequently experienced issues with their holding tanks overflowing. DMC used sensor readings in the central Schneider M340 PLC to implement logic which would disable all offload pumps if the holding tanks reached a user-configurable high level setpoint.

DMC’s additional logic also helped the customer to improve their shutoff capabilities. By implementing centralized pump control, DMC allowed the customer stop all functionality from a single location. Prior to DMC’s involvement, the customer’s shutoff capability was limited to certain sections of the facility.

Customer Benefits

  • Effective high level monitoring to avoid costly and disruptive spills
  • Centralized pump control
  • Improved safety shutoff capability
  • Flexibility to upgrade facility in the future


  • Schneider Modicon M340 PLC
  • Schneider Unity Pro