Developing automation of state of the art, multi-rooms of multi-unit automation and testing for a large air-conditioning manufacturer

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"The NI hardware and LabVIEW development platform provided us with everything that we needed to develop a complex system from scratch in relatively short amount of time, and with very few surprises."

- Eli Sabag, SK Electronika

The Challenge:
Design, develop and deploy a flexible automation and long term testing system for variations of multi-room, multi-unit testing, which included several components for physical simulation of different environment conditions.

The Solution:
Using several CompactDAQ and C Series modules for measurements and control, together with Object Oriented, highly parallel, LabVIEW code.

Author(s):
Eli Sabag - SK Electronika

SK-Electronika Ltd, provides solutions for a wide range of clients from diverse disciplines such as: medical, telecom, printing, automation, aerospace, military & defense, semi-conductor, electronics and machine vision.  
We were approached by Electra, a large manufacturer of Air-Conditioning units to provide a hardware and software solution to operate their newly built, state of the art, air conditioning testing rooms. 
The facility was designed not only to meet it’s quality assurance needs, but also to give Electra a competitive advantage over its European competitor for having one of the most advanced testing operations.

Testing Facility:
The testing facility includes 4 pairs of rooms, each for testing up to 4 units. In each pair, there is an “outdoor” section, which contain up to 4 condensers, and “indoor” section, which contains the 4 evaporators.
In order to simulate different operating conditions, 7 of the rooms contains an “Environment” heaters and Air-Conditioners. The last room, which simulates freezing outside temperatures for the condensers, is basically a large refrigerator, which contains the condensers.
Energy conservation was an important consideration, so 4 centrifugal fans were installed between each pair of well insulated rooms (except for the one with the refrigerator “outside” section). The fans are programmed to work in concert with the all other devices in the room (and with regard to the testing modes of the UUTs) in order to reach the desired testing temperatures with minimum amount of energy expenditure.

Control and measurement Hardware:
A CompactDAQ chassis for each pair of rooms, with two NI 9213 C series modules for temperature measurements, one NI 9201 for current and voltage measurements, and three NI 9482 Relay modules for device control. For current and voltage temperatures, VeriVolt sensors were used.

General Software Requirements:
- Ability to control and monitor 1-4 testing rooms in parallel from each workstation (2 workstations were planned to begin with)
- Support of manual and automatic testing
- Flexibility:
• Control slightly dissimilar hardware configurations from the same executable. This was needed in order to both support the refrigerator room, which does not include the fans and only has physical connections to 3 UUTs, and to allow for additions and movement of thermocouple modules without rebuilding the application.
• Control a few testing rooms at once and that each room had its own configuration and even each UUT had its own cycle pattern.
• Placement of thermocouple sensors can be modified from test to test, so sensor placement and naming screens were needed for dynamic naming of graph plots and report headings.

Software Architecture:
- LabVIEW 2013 for development
- The StateChart toolkit was used for environment control
- Object Oriented was chosen mainly for data encapsulation
- Event driven architecture throughout the application

Software Design:
- Producer/Consumer design pattern was used for control, acquisition, display, and reporting.
- Communication between the components was done using Queues.
- Dynamic dispatching of asynchronous components was used to allow independent operation of chosen test rooms in parallel
- Simple configuration screens allow maximum flexibility.
- The UI mimics very closely the actual testing rooms (even including a bit of animation), and thus, it is very intuitive to the users.
- Considering the Object Oriented and Event Driven architecture of the application, we were able to simplify the code in such a way that we were able use only a very small number of running loops to iterate between rooms and components.

These architectural and design decisions proved to be very helpful. They provided the flexibility needed and helped in avoiding data collision and thus, made the debugging much simpler.

The NI hardware and LabVIEW development platform provided us with everything that we needed to develop a complex system from scratch in relatively short amount of time, and with very few surprises.

Author Information:
Eli Sabag
SK Electronika

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