Control systems integration for full automation

Build a strong foundation for smart data collection by investing in appropriate network infrastructure.

By Chris Marinucci

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Data collection and data analytics are the foundation of continuous improvement, but implementing a process to collect and analyze data on existing equipment rarely offers the return on investment to survive the budgeting process as a standalone project. A solution is to build the foundation for data collection and analytical capabilities into a project up-front. A small investment in the correct network infrastructure, programmable logic controller (PLC), or supervisory control and data acquisition (SCADA) systems can have a tremendous impact on operations without breaking budgets.

For a good illustration of the process necessary for realizing a data collection and data analytics solution, consider the process put in place for a standalone production cell that expertly performs specific tasks while conforming to AMS-2750E, a national data collection and integrity specification for the aerospace industry. If you replace this industry specification with any other requirement from a governing body (i.e., FDA, USDA, EPA, or DEC), the process of integrating those requirements into your process will remain the same.

The purpose of this production cell is to heat parts for a particular time to a specific temperature in an atmosphere where the level of carbon also is controlled. By adding hydrocarbon-based liquids and gases into the 2000 deg F furnace, carbon can be driven or removed from the parts while simultaneously changing the structure of the material to make it stronger. Even more crucial than the heating is the cooling of the part in a fixture to help it maintain the intended shape. Because of the use of a robot, as well as the introduction of flammable liquids and gases into a 2,000F furnace, there were safety standards to meet as well as process control and quality criteria to uphold. To manage these requirements, the following automation components were selected:

  • Honeywell Flame Safety Relay
  • Allen Bradley Guard Logix Safety platform
  • PanelView Plus V6 operator interface
  • FANUC R2000iB/210F six-axis robot
  • Inductive Automation Ignition SCADA

All manufacturing processes have one thing in common: field-mounted sensors and instruments that tell us how a process is performing. It does not matter whether these components are connected to an automation platform or have local displays for an operator to manually record data into a log book. The first step in collecting data is to concentrate the data into one location, or in this case, clusters of instruments in multiple locations.

A programmable logic controller (PLC) from Allen Bradley provided a one-stop-shop for data collection, as well as process control. Data from the instruments and sensors was brought to the safety PLC using standard wiring methods, 4-20 ma analog signals, and discrete digital signals. Input/Output(IO) devices were concentrated on different pieces of equipment within the cell. In addition, the cell needed to easily break down for shipping, leading to the use of Allen Bradley’s Point IO. The Point IO panels were placed on various pieces of equipment in the cells where the instruments for that piece of equipment were wired. In addition to the instruments, numerous variable frequency drives needed to be controlled. In this case, a different approach was taken by controlling and monitoring these drives over a network connection instead of discreetly wiring them.

To network the Point IO panels and variable frequency drives (VFD) back to the safety PLC, an Ethernet ring topology was chosen to allow each device two communication paths back to the safety PLC, creating network redundancy. Two Ethernet cables were run to each Point IO block and VFD to support both safety IO, as well as standard process control IO. This reduced the amount of field wiring that needed to be performed when the cell arrived at the client’s site for final installation as the local device wiring for each component in the cell was left intact for shipping. Only the network cables and power for each piece of equipment needed to be run by the local electrician.

To collect data from the FANUC robot, a similar approach was chosen as the VFD and used an Ethernet connection talking the Ethernet IP protocol between the robot controller and safety PLC. By using an industry standard cabling solution like Ethernet and talking a standard industrial protocol over that cable like Ethernet IP, vast amounts of performance and diagnostic data could be collected about the robot and VFDs. An additional benefit was the precision of commands to these devices through using a networked solution verses a traditional wiring approach. The process and diagnostic data were seamlessly presented to the operator through the PanelView Plus graphical interface, which performed and felt like an integrated cell even though there were multiple controllers and devices in the cell from various manufacturers.

A choice had to be made for this internal network for the point IO, robot, and VFD communications: Ethernet or ControlNet. Given that both network solutions supported the required safety features, the decision fell to cost and component integration. Ethernet components, such as cabling, termination devices, and network appliances like switches, are numerous, making the Ethernet versions more cost effective than the ControlNet equivalent. The decision to use Ethernet was further supported because Ethernet IP is a readily available communication option for the FANUC robot. Lastly, most Ethernet based components come with Web servers. This was important for remotely supporting the cell over a secure virtual private network (VPN). Although web servers are not used for process data, they have proven to be a valuable troubleshooting tool for engineers and technicians. With an eye toward the future, most specialty analytical equipment has an Ethernet-based communication option using various industrial protocols. Using Ethernet gave our client options to integrate well with future technology.

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