POWER September 2013 - 28

with devices using other protocols such as GSM, ProfiNet, or OPC
and can communicate with programmable automation controllers
and Bently Nevada vibration systems.
Network Architecture
The new system offers redundancy in both the servers and the
network. It is based on a client/server architecture that is both
reliable and robust. The servers are used to communicate directly
with the Mark Vs, while the clients communicate solely with the
servers, reducing overall traffic and reducing the communications
load on the  core of the Mark V (Figure 6). With this structure,
the server can connect to up to 16 Mark Vs at once, which makes
it highly scalable.
The new network layout offers redundancy for both the data
servers and the clients. Redundancy is key to creating a robust
system that can withstand hardware failure. The TMOS system has
automatic failover capability, where the clients sense when their
connection to the server has been lost. This could be caused by
a multitude of issues, including severed network cabling or failed
network cards. The clients can automatically and seamlessly
change servers and continue to function, while maintenance can
be performed on the faulty server.
Hard drive failures are always a possibility, and if the system
has not been designed correctly or regular backups have
not been made, they can be catastrophic. This issue was addressed
in the new system by use of a redundant array of
independent disks (RAID), in this case RAID5. If any single
drive fails in the server, the RAID controller can rebuild the information
that was on that drive, making the failure invisible
to the end user. An indication from the hard drive controller
alerts the user of the problem, and the offending hard drive
can be hot swapped with a replacement drive without needing
to take anything offline.
Smooth System Installation
The entire upgrade was performed without requiring an outage.
This was possible because the new HMI computers were
installed and commissioned alongside the old HMIs and were
operated simultaneously. The new HMI was brought online,
commissioned, and tested in operation for some time before
the old HMI was decommissioned. Thus, no HMI or control
system downtime was necessary. The new system utilized
the original site files in the unit directory. These files were
parsed and used by the TMOS software. Much of the new HMI
setup and configuration was performed before the hardware
was shipped to the site, reducing required site time and thus
reducing costs.
In order to ease the transition to the new graphics and
learn the new system, the old HMIs were left in place for a
few days while the customer was given training on the newly
installed machines. At the end of this period, the old HMIs
were decommissioned and removed. Also during this training
period, the graphics were tuned to suit the customer's needs.
An important part of any HMI replacement is customization
of the graphics to meet expectations and unique preferences
particular to each site. ■
-Contributed by John Sprague, senior project engineer with
Turbine Technology Services Corp., Orlando, Fla.
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POWER September 2013

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