Emerson Exchange 365

More isn't always better, but it certainly is when it comes to securing a few additional process variables from 85 wireless vibration transmitters at the Savannah River Site (SRS) tritium gas-bottling facility near Augusta, Ga.

The 100-acre SRS Tritium facility is the smallest of the many sites at the U.S. Dept. of Energy's vast Savannah River Nuclear Solutions facility, which manufactures and reprocesses much of the nuclear fuel and other materials used in U.S. nuclear weapons. However, despite its size, SRS Tritium also has one of the site's most important jobs, which is extracting and packaging tritium to replenish the nation's nuclear stockpile. As a radioactive isotope of hydrogen, tritium must be continually replenished because it radioactively decays 5.5% per year.

Quest for health variables

"The problem was we have 85 wireless transmitters on our 9420 vibration components, each with two accelerometers/transducers and two outputs, but that only gave us four HART variables that are occupied by the transducers," explained Bob Fogle, process control engineer, Savannah River Nuclear Solutions. "We simply needed more data, such as battery voltage and other device-health variables, so we could predict when components would need to be changed out. At first, it looked like we were going to have to give up one of our original four HART variables."

Fogle and Tommy Patterson, senior systems engineer at R.E. Mason, presented "Getting the Most Out of Wireless with OPC" at the Emerson Global Users Exchange this week in San Antonio. Fortunately, Patterson serves as onsite DeltaV resource at STS Tritium, and he, Fogle and their colleagues devised a solution that delivered the much-needed variables by employing OPC communications.

"The required variables and information were already in the transmitters," said Patterson. "We just needed a way to get them on the OSIsoft PI software on our desktop PCs."

Seven-step parameter program

Patterson reported there were seven basic procedures required to gather the added variables, and move them via OPC to the PCs at SRS Tritium. They include:

• Create an OPC-ready account to run its services. The account must be a DeltaV and Windows user; have access to the plant area where the OPC values will be written; have privileges to run a service; and meet the user's cybersecurity requirements.
• Map desired OPC parameters in the gateway. This enables the Emerson 1420 wireless gateway to be used for OPC communications. The gateway is an OPC server, and the parameter paths must be specific with no misspellings.
• Install a security proxy. Each gateway is shipped with security proxy software. However, the software must be installed on a DeltaV server that can contact the gateway, and the server must be where the OPC server resides. After the security proxy is created, it will show up under the gateway access list as an available OPC server.
• Install an OPC Mirror from DeltaV. This requires a license. It must be installed on the same servers as the proxy and the DeltaV OPC server. Then set the new account to run the proxy and OPC Mirror.
• Build, configure or modify control modules. First, if analog values are being passed, configure the parameters as floating points. Again, remember to give the new account access to the plant area, where the control modules are assigned. Also, remember to assign the plant area to the workstation where the proxy and OPC Mirror are installed.
• Build and open software "pipes" in OPC Mirror, which is possible because it's a DeltaV application that allows different servers to talk to each other. The left side of the display is the gateway, and the right is the OPC server.

"When you create a new OPC proxy, it must include the IP address. You must also turn on security because the devices must be trusted in order to share data," explained Patterson. "They also have to exchange certification confirmations. It's also very important to save these configurations. If you do this tasks before, it will make life easier now, and there will be less troubleshooting needed later."

Patterson added that OPC Mirror is essential because it bridges the gap between servers that usually can't communicate, and allows them to talk to each other. "Opening OPC Mirror lets users browse for parameter paths," he added. "It's also important to set the data type as ‘VT empty’, so the system will automatically assign data types. Again, you must remember to save pipes after they're created.

"The main aim was to get those battery voltages and other parameters, so we mapped to them, accounted for biases, and ran them for a while. They worked and continue to work, and we now have the ability monitor battery voltage directly on DeltaV. Plus, our maintenance department can access this data through OSI PI. In the future, this added data will help with other wireless projects at our facility."