Case Studies

Conversion of Hybrid Rockwell Control System to Siemens with S120 Drives

Posted in HMI and SCADA, Manufacturing Automation and Intelligence, PLC Programming, Siemens PLC, Specialty Machinery


DMC worked with a carbon fiber manufacturer to convert their system to use only Siemens controls hardware. The client initially had a hybrid system consisting of an Allen-Bradley PLC and distributed I/O, but Siemens drives were used due to their advantages in dusty environments. Impressed by the diagnostics tools available on Siemens PLCs, the customer later decided to switch entirely over to the Siemens platform.


DMC worked with a carbon fiber manufacturer to convert their Rockwell/Siemens hybrid system entirely to Siemens. The client’s facility includes a web-handling machine where carbon fiber is woven through many rollers, which are located throughout several ovens. As the fiber travels through the ovens, it is heated, which leads to shrinkage. To accurately control the amount of shrink, it is necessary to modulate the tension of the fiber across each of the rollers. DMC worked with the client to add new software features to control this tension.

The machine was initially designed with an Allen-Bradley control system, but Siemens S120 Drives were chosen for their better impermeability to dust compared to similar drives. Carbon fiber dust is highly conductive, which could lead to an electrical short if it gets into the control cabinets. Although the application required only speed control, for which a Siemens G120 drive would suffice, the client chose the S120 drive due to these environmental considerations.

While DMC replaced most of the controls system, neither the machine itself nor the field wiring was modified. All changes were limited to the electrical cabinets. DMC assisted the client in swapping out the PLC and remote I/O system for Siemens hardware. DMC was then able to reconfigure the S120 drives from using Rockwell’s EtherNet/IP protocol over to Siemens’ PROFINET protocol by changing a single drive parameter.

siemens hardware

One major benefit to standardizing on Siemens across all plant hardware is the built-in PROFINET diagnostics tools. With only a few clicks, a feature-rich diagnostics viewer can be added to any WinCC HMI. This addition provides the operator with detailed diagnostics information for all connected PROFINET devices (including PLCs, I/O systems, drives, and more). This feature was one of the driving forces that lead the client to convert to the Siemens platform fully, and they have been happy with the benefits it provides.

siemens hmi

In addition to the PLC and drives updates, DMC also refreshed the HMI for a cleaner, more intuitive user interface. The client had already started the process of converting from an Allen-Bradley PanelView Plus HMI to Siemens WinCC Comfort. DMC completed this process for the client and spent any available time while onsite refining the look and feel of the HMI screens. The client was delighted with the HMI improvements that DMC completed with only a few hours of work.

Before departing the client’s facility, DMC also offered hands-on controls training so the client could be more self-sufficient with future updates and maintenance. We collaborated with their engineers and reviewed the PLC and HMI programs in full, so they would not always have to depend on DMC to make minor changes to their system.

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Customer Benefits

  • Platform consistency throughout the plant 
  • Updated PLC code base for modularity and scalability
  • Updated HMI interface for an improved user experience 
  • Built-in diagnostics over PROFINET, which provides more detailed information on hardware/software errors