Gateway to process automation
Valspar Corp. is the third largest paint and coatings company in North America, and the sixth largest in the world, with plant production totaling near 250 million gallons of paint annually. Meter Maintenance & Controls Inc. (MMCI), a system integrator based in Redlands, CA, that specializes in turnkey liquid measurement solutions, has set up or retrofitted five Valspar plants around the U.S. and elsewhere. New Valspar plants receive a top-to-bottom paint blending and batching system, with everything from the piping, to the electrical, to the process equipment being supplied, installed, and programmed by MMCI.
To handle the paint blending process, MMCI uses Emerson Process Micro Motion flowmeters to measure mass flow, volume flow, density and temperature variables, and provide precise control measurement of the various ingredients that create a given batch of paint.
From a management and operation standpoint, Valspar wanted a system that would allow the entire enterprise to be integrated from the plant floor controls to the information systems. Plant operators need diagnostic information for monitoring of the process and for identifying maintenance needs or problems on the line without requiring that the operator be trained on the control system. The laboratory also needed access to this information for quality control and trending.
MMCI chose to use a Rockwell Automation process automation system (PAS) to extract data from the flowmeters. As each flowmeter batches a raw material into a mixing tank, the process variables are recorded by Rockwell Automation RSSql software and ultimately presented to the Valspar operators in a Rockwell Automation RSView human machine interface (HMI). In RSView, an alarm system is implemented with predetermined setpoints that, when triggered, alert the operator and provide cues indicating the proper action to be taken. These process variables are also pulled into RSSql to give Valspar’s laboratory access to historical data for all past batches.
With the preferred pieces in place, MMCI had one more problem to solve: a way to communicate between the ControlLogix PAC and the flowmeters.
Emerson developed the HART (Highway Addressable Remote Transducer) multi-drop protocol in the 1980s, so the programmable Micro Motion systems communicate via that protocol. HART is a highly accurate and robust protocol, making it ideal in process industries, but to push this diagnostic information through to the HMI, MMCI needed to convert this data to Rockwell Automation’s EtherNet/IP protocol.
Mike Smith, programmer and systems engineer for MMCI, says that Rockwell Automation Ethernet communication is preferred by MMCI because it allows MMCI to bypass the creation of communication software codes. “With other providers of HART interfaces we have used,” Smith says, “we have needed to use an OPC server to collect and distribute the information, which required that we write our own code.”
Terry Davis, president of MMCI approached Tom Thuerbach, branch manager for Royal Wholesale Electric in Riverside, CA, to help him find a solution to convert the HART data to Ethernet/IP. Thuerbach recommended ProSoft Technology’s EtherNet/IP-to-HART multi-drop communication gateway.
All of the five plants MMCI has set up for Valspar involve between 30 and 50 flow meters. In a general application, MMCI has all HART flow meters linked up to a single ProSoft gateway. The gateway routes the data over Ethernet to the Rockwell Automation ControlLogix PAC. The ProSoft module acts as a bridge, allowing the Process Automation System to communicate with the flow meters. Once data is extracted from the meters, it can be distributed to RSSql and RSView.
Maintenance and quality benefits
“Our plants are happy with the feedback that we are now receiving from our meters,” says Mike Dimaggio, the director of engineering for Valspar working out of the company’s North Carolina facility. “Using this information we have been able to modify our preventative maintenance plans to stay ahead of any issues before they occur.
“For example, we began changing out filter bags before the pumps and meters. In the past, if the bag wasn’t changed out, we would reduce the flow to the point that we would have meter inaccuracies. Now that the system tracks this data, we have been able to see how often we should be changing these bags to avoid any errors when batching, and are able to act before an error occurs.
“Also, in the past if someone had a theory that a metering problem caused a quality issue with a batch, we could not prove or disprove them,” continues Dimaggio. “We had to look at the meter the next time it was used. Now, with stored data several times per minute for each meter charge, we can go to the real data from the questioned charge and either prove or disprove this theory. The ability to avoid meter inaccuracies will definitely help us from a quality standpoint.”
Dale Simmons, lead engineer for Valspar working out of the company’s Illinois facility, says, “With the HART system, we can track and standardize flow rates of materials between sites. We also use the density outputs to monitor solids levels in our slurry tanks. Logging the history enables us to track line cloggages and take preventive action.
“In several situations we have used the historical HART data in conjunction with RSSql to troubleshoot issues that have occurred within the batching system itself. These types of issues range from meters faulting out and misdirected flows to incorrect RSSql transactions.”
From a monitoring and operations standpoint, the process allows any person in the plant at any given time to view activity on the floor, the Watch Dog Timers (a piece of hardware that can be used to automatically detect software anomalies and reset the processor if any occur) set up by MMCI, and any other critical information connected to the system. This saves money and time for Valspar associated with hiring and training employees, plus the rework and maintenance that would otherwise have to be done by a technician. The system is considered by Valspar to be user-friendly and because the measurement system is so accurate, the system nearly runs itself and downtime is mostly eliminated.
“I know Valspar appreciates not having to call us out there every time they run into a maintenance hickup,” notes Davis.
As a result of the success MMCI experienced with Valspar, Davis says, “Now we try to use ProSoft’s HART gateway in all the paint plants we work in, and have plans to apply it in many other industries we serve.
|Adrienne Lutovsky is a public relations specialist at ProSoft Technology, which makes more than 400 communication interface modules supporting more than 60 different protocols.|