What’s the secret to providing superior
service and staying competitive in a
changing market? Well, you might
learn something from Alta Refrigeration’s experience.
Over 10 years, it transformed itself from a
custom engineering services company into a scalable
industrial equipment manufacturer using an
edge-oriented control architecture to efficiently
manage a growing installed base.
Alta has been designing and installing refrigeration
systems across the United States for more
than 45 years. For many years, these systems
were large, custom-designed systems that used
a central machine room to deliver refrigerant to
various facility areas through long, overhead piping
runs. Due to their size, these systems required
significant time to design and program, and competitors
were able to steal some of their market
share with cheaper, simpler offerings.
“Competitors could use 20-30 cheaper units
with control limited to a dumb thermostat to compete
against one of Alta’s large systems,” says
Peter Santoro, controls engineer at Alta.
Alta knew it couldn’t compete by reducing its
product quality, so the company looked for a way to
standardize its offering without sacrificing features.
We’re the Experts
In 2013, Alta introduced its Expert series of
modular refrigeration control units. Each unit
uses a standard, reliable design and can be
mounted on the roof above the area it served,
simplifying installation.
“A single Expert has almost as much I/O as an
entire centralized system and, because the units
are much smaller, the wiring and conduit runs are
incredibly short, allowing us to cram in a ton of
sensors,” explains Santoro. “The units themselves
are also incredibly efficient. We analyze external
ambient conditions and refrigerated space and do
real-time thermodynamic calculations. This lets
us do variable capacity refrigeration, and only run
exactly the amount of refrigeration as needed.
All motors are on variable speed drives. We also
design many of the sensors we use on the system, allowing us to get precise valve positioning and
monitor refrigerant levels throughout the system.
We make good use of Hall effect sensors
in various configurations to monitor refrigerant
levels and motor positions. There is also a
dedicated energy monitor on each unit so we
can monitor voltages and power usage.”
Since all Expert systems are essentially
the same, Santoro and his colleague, Todd
Hedenstrom, were able to focus on creating
a robust and complete solution that works for
many different applications.
A good problem to have
Market response to Expert has been very positive.
Alta has sold nearly 600 units and is typically
sold out into the next year. But growth
brings its own challenges. With only a small
controls engineering team, servicing the growing
installed base became time-consuming.
Adding to this time crunch, some aspects
of Alta’s previous designs related to system
maintenance issues. For example, the control
system required numerous steps to properly
update control strategies in the field, including
exchanging files between the control engine
and the web server used for remote connectivity.
And because Alta had previously left the
details of remote connectivity to each customer,
this increased the team’s workload by
requiring them to check in on each site every
day using different methods—such as VPN,
Citrix, LogMeIn, and TeamViewer.
Alta’s centralized control system design was
built around an industrial PC (IPC) running
custom C++ code on top of a distributed I/O
system from Opto 22. When designing Expert,
this control system was simplified by replacing
the IPC with an Opto 22 PAC (programmable
automation controller).
Though this change was an improvement
because it allowed for all the components of
the system to be managed through the PAC,
it still required a multi-step update process
and didn’t provide as much data access as
Alta wanted. This led Alta to explore use of
Opto 22’s groov EPIC (edge programmable
industrial controller) system.
EPIC supports all the power, I/O, communications,
storage, and networking functions
of an IPC and PLC on a single backplane
without the complexity of maintaining a full
Windows OS environment.
Web interface
via the controller
Santoro and Hedenstrom started by using groov
EPIC’s operating system shell to port their PAC
application to C++.
The new program controls the installed I/O
modules—voltage and current sensing inputs
and discrete AC outputs—using Opto 22’s C++
OptoMMP SDK (software development kit). The
application also includes its own Modbus server
that creates and manages connections to variable
frequency drives, the local energy monitoring unit,
and other remote devices.
“We [also] have our own REST API and webserver
running on the C++ application,” Santoro
adds, “allowing us to create our own web page
interfaces in HTML and Javascript,” such as a
Google Chart API (application programming
interface) to display energy metrics in the HMI.
Each Expert web interface is served from an
EPIC controller. The interface includes prebuilt
templates for different unit configurations and
verifies system settings to help technicians identify
configuration values that are out of range or not
recommended. It also generates alarms as needed.
Alternatively, customers can access unit data
through the Expert’s Modbus server or REST API.
For managing groups of Experts, Alta uses a separate
HMI server to read data from each unit and
present a unified view of the entire system. “All of our
sites are required to have a local interface for operators
to see a global view of their refrigeration units,
instead of having to manage network connections to
hundreds of individual units,” Santoro explains.
To create this site-level HMI, each Expert stores
transient data in the shared memory scratchpad area
of the groov EPIC. Alta’s HMI server runs on Windows
and uses Opto 22’s .Net OptoMMP SDK to
retrieve data from all units in one-second increments.
Data is stored in cyclical files that maintain a oneweek
buffer, and the HMI server uses this data to
generate trends, charts, and email notifications.
Alta can also access this data remotely for troubleshooting
recent events. By default, groov EPIC does
not route traffic between its Ethernet ports, so Alta
can use the controller to create a security zone for
each Expert. One port on each EPIC connects to
a private network exclusively for the controller and
its remote devices. The other port is connected to a
common network between all the units at a given site,
as well as the local HMI server.
This server is connected to the internet and uses
MQTT to send and receive data, acting as a middleman
for each individual Expert to the MQTT broker
that resides in Alta’s headquarters. When Alta’s
remote HMI requires new data, it sends a request to
the local server over MQTT. The data is then queried
and sent back. External connections to local HMI
servers are restricted so that the only traffic allowed
through is from outbound MQTT TLS connections.
Recently, Alta also made it possible for customers
to access this remote server. The server has its own
database that records temperatures and energy usage
for each Expert in 10-minute intervals.
Nationwide data
aggregation
Using groov EPIC, Alta has now built a nationwide
HMI that aggregates data from its network of
Expert units and highlights any issues the team
needs to act on. Instead of spending hours every
day to check on each site, they can monitor their
entire installed base in minutes. They know when
there is a problem, can input and track necessary
work orders, track technicians’ locations, and
monitor energy usage per unit. When an alarm
occurs, the system creates an interactive timeline
of events before and after the alarm event.
“Often, we know what the problem is before the
customer calls. We just need to drive there and fix
it,” says Santoro. “With the amount of data we get
from our units, we are capable of diagnosing the vast
majority of problems remotely. This allows many of
our end users to not even staff on-site maintenance.
And there’s no interfacing with third-party systems
anymore. It’s all integral.”
Servicing the systems themselves has also become
much simpler now that Alta can manage the entire
platform—I/O configuration, control strategy, communications,
and networking—through a single
device. “One of the best features we introduced was
the ability to update the programs through our web
interface. Now a batch program packages all the program
files into a .gz (compressed) file. Technicians can
upload the file and restart the system,” Santoro says.
Alta also uses the groov EPIC’s touchscreen as
a maintenance interface inside the control cabinet.
The native groov Manage application allows
them to view and modify I/O and network settings
directly on the controller without using a separate
computer interface. Using the EPIC’s native HMI
server, groov View, Alta also provides technicians
with local control options and basic information
about the Linux program’s status.
