Customer Solutions

CiDRA Corporation Cuts Costs with NI LabVIEW-Based Resource-Sharing System

Author(s):

Keith Brainard, Bloomy Controls

Industry:

Telecommunications

Product:

GPIB & Instrument Control, LabVIEW

The Challenge:

Distributing access to a powerful and expensive GPIB instrument throughout a company and regulating access to the device for multiple users. Ethernet

The Solution:

Creating a system to effectively share the instrument using a National Instruments GPIB-ENET/100 module, an NI LabVIEW-based client-server architecture, and a queuing mechanism.

Introduction
Several groups within CiDRA Corporation, a manufacturer of high-performance optical modules and monitoring systems for optical networks, photonic test, measurement instrumentation, and other industrial applications, needed access to a dispersion analyzer for testing. Because a single dispersion analyzer costs up to $250,000 and each group’s need for the instrument is high but inconstant, the company needed a low-cost alternative to purchasing one for each group. Using NI LabVIEW and a GPIB-ENET/100 module, NI Select Integrator Bloomy Controls made it possible for several groups to share access to a single dispersion analyzer, saving time and money for CiDRA while enabling each group to take measurements when needed.

Distributing Access with Flexible Hardware
The Advantest Q7750 Dispersion Analyzer measures chromatic dispersion of optical network components. One option for distributing access to this instrument is to roll it on a cart to each lab as needed. However, the stress of moving the dispersion analyzer could cause damage to its precision optical components. Rather than bringing the instrument to the user, we chose to bring the user to the instrument.

The dispersion analyzer communicates with a host PC using GPIB. While GPIB is a powerful communication method, it imposes distance limitations. A user cannot separate any two nodes on a GPIB network more than five meters without risking loss of data due to timing issues. Using an NI GPIB-ENET/100 module, we solved this problem. Because the GPIB-ENET/100 converts between GPIB and Ethernet signals, users can access GPIB devices via an Ethernet connection. The distance limitations on Ethernet protocol are far more flexible, so users throughout CiDRA’s building can use the instrument via the GPIB-ENET/100. This architecture would not have been possible without this module.The system uses a JDS Uniphase SC Series optical switch to switch in the fibers for individual users. The fiber running from each station to the optical switch are short enough to avoid any adverse effects on the dispersion readings. The dispersion analyzer also provides a setting to compensate for fiber runs longer than 1 km.

Standard PCs are the final hardware component in this system. Client PCs make dispersion measurements, while a server PC regulates access to the instrument. The client PCs collect, process, and archive dispersion data. They also place requests to the server to gain access to the instrument and provide a user interface to the dispersion measurement process. The server PC processes access requests from the clients and alerts clients when it is their turn to use the instrument. Additionally, through the server’s user interface, users can monitor dispersion analyzer client activity. The client PCs and server PC are on the same network, connected to the GPIB-ENET/100, which we connected to the dispersion analyzer and the switch.

Regulating Access with Intelligent Software
Using NI LabVIEW, we combined the GPIB-ENET/100 and all of the PCs into one system. With NI LabVIEW, users can communicate with the dispersion analyzer to collect data, take advantage of data analysis and storage capabilities, and control access to the instrument using priority-based queues.
Using virtual instrumentation software architecture (VISA) in LabVIEW, we created a program to automate front panel interaction. The system automatically pushes a repetitive sequence of buttons on the front panel of the instrument much faster than any human can. Furthermore, because NI LabVIEW collects the data, this process eliminates the need for data entry.

VISA also provides an important tool that helps regulate access to the dispersion analyzer. A VISA resource lock on the GPIB-ENET interface prevents users from circumventing the client-server system to gain direct access to the instrument. In addition to performing the instrument-related actions, the client PCs interface with the server PC to determine when it is appropriate to access the instrument. Each client PC interacts with the dispersion based on settings read from a configuration file. This enables engineers to configure tests without the operators needing in-depth knowledge of the analyzer. The client PCs also store data collected from the instrument and analyze the data to determine a pass/fail result of the testing the user is performing. Finally, LabVIEW prints a report sheet.

We extended this system architecture to work with a workgroup network topology. Client PCs within a workgroup normally cannot access IP addresses outside their workgroup. However, proxy servers using VI server technology give the clients PCs access to the instrument.

Saving Time and Money with NI Tools

The system we developed provided CiDRA significant time savings. If not for this system, users would have to waste hours waiting in a physical line near the instrument while others are using it. Instead, users can perform regular work duties while the software waits in line for them. Furthermore, because the software controls this instrument, it is now possible to perform overnight testing, using the system without incurring overtime costs for the dispersion analyzer users.

By sharing access to one dispersion analyzer, CiDRA saved an extensive amount of money. CiDRA currently has many deployments of the dispersion analyzer client software, each used in slightly different ways.
Thanks to the complete set of tools NI provides, we created a system that enables multiuser access to one primary system, eliminating the need for additional instruments. By giving multiple users remote access to the Advantest Q7750 Dispersion Analyzer from locations throughout the building, this system saved significant time and money for CiDRA.

For more information, contact:

 Keith Brainard

Bloomy Controls, Inc.

839 Marshall Phelps Rd.

Windsor, CT 06095

Tel: (860) 298-9925

Fax: (860) 298-9535

E-mail: keith.brainard@bloomy.com

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