|
 |
test&measurementZONE Products for the week of June 16, 2008
ICS Electronics Says ...
Model 8055 Ethernet To Instrument Interface
ICS Electronics announced a new Ethernet to GPIB Instrument Interface that adapts GPIB instruments to Ethernet-based test systems. Called the Model 8055, this new interface provides access to GPIB instruments from any computer with a NIC interface or over a TCP/IP network. Typical uses are adapting expensive GPIB instruments to LXI or Ethernet-based test systems or sharing GPIB instruments among several users on a company network.
The Model 8055 is a VXI-11.3 compliant Server. Combining the 8055 with an IEEE-488.2 GPIB Instrument converts the GPIB instrument into a VXI-11.3 compatible instrument that can be readily controlled by programs running in both Windows and UNIX/LINUX type operating systems. Windows users can write test programs that make VISA calls. Both National Instruments and Agilent VISA libraries communicate with VXI-11 instruments. UNIX/LINUX and UNIX like operating system users (SUN, HP, Apple etc) can convert the VXI-11's RPC library into library files that can be called by C or JAVA programs.
VXI-11 is a communication standard developed by the VISA Consortium in 1995 in conjunction with the VISA Specification. The VXI-11.3 sub-standard covers LAN-to-Instrument Interface servers like the 8055.
The 8055 is different from the existing Ethernet to GPIB Gateways that are used to control GPIB instruments over a company network. These existing GPIB Gateways are remote GPIB Controllers, handle multiple instruments and are 'gpib0' VISA resources. The 8055 is designed to convert a GPIB instrument into an Ethernet-based instrument and is an 'inst' VISA resource. The 8055 can be an external box or mounted inside an instrument and gives the user the option of controlling the instrument from the GPIB bus or from the Ethernet port.
ICS's 8055 Ethernet-to-GPIB Controller has several unique features: First the 8055 is 100% VXI 11.3 compliant which is an open communication standard. The 8055 supports reverse channel Service Request messages to alert the client application when an event occurs. The 8055 also supports multiple clients as part of its standard firmware. The 8055 is a RoHS compliant assembly for use in products aimed at the European market.
The Model 8055 ships with ICS's VXI-11 Keyboard utility program and Configuration Utility. The Configuration Utility lets the user set the 8055's network settings and enter the instrument's GPIB addresses into the inst conversion table. The 8055 can handle instruments with up to 16 GPIB addresses. The VXI-11 Keyboard lets a user interactively control the 8055. Both utility programs run in a WIN32 PC.
ICS Electronics is a pioneer and leader in the design and development of IEEE 488/GPIB, Serial and VXI bus products. The 8055 is the latest member of ICS's family of VXI-11 Interface products.
EN-Genius Says…
The IEEE-488/GPIB (General Purpose Interface Bus) has been around a long time (since 1975, to be exact), and although it's been supplanted in many test racks by the likes of USB (Universal Serial Bus) and LXI (LAN eXtensions for Instrumentation), there are still a lot of GPIB instruments kicking around. This clever product from ICS Electronics potentially extends the life of this legacy equipment, and opens the doors for true Internet-enabled remote control.
 These days, vendors are touting LXI timing, packaging, and human interface uniformity. But, LXI doesn't specify a communication protocol. It requires that LXI instruments use an undefined VXI Discovery Method. And it doesn't require that LXI instruments be IEEE-488.2-compliant. They must only respond to an "*IDN?" query. LXI users therefore have to check an instrument specs to be sure that it's VXI-11.3 and IEEE-488.2 compliant. If not, they’re restricted to controlling a given piece of test equipment through vendor-supplied IVI (Interchangeable Virtual Instrument) drivers and other vendor-supplied programming approaches. It’s not a very universal or interchangeable approach at all, to say the least.
An 802.3 Interface
This is where the ICS Model 8055 Ethernet-to-GPIB instrument shines. As a $550 box, it essentially puts a LAN interface on any GPIB instrument. The 8055 internal Web server dishes up HTML Web pages for viewing and setting the 8055 network settings. The system permits the GPIB instrument to communicate bi-directionally at 180 kbyte/s using IP (the Internet Protocol). All your host PC needs is an IEEE-802.3 LAN port. It can be an older 10-Mbit/s 10Base-T Ethernet port, or an all-out 100Base-T port cranking at 100 Mbit/s.
 You can actually operate the test gear through a Web browser. The browser, or a config utility supplied by ICS, can configure the 8055. The box will work using static IP addressing, or it can accept a dynamically-assigned DHCP address.
Once set up, the Model 8055 adds VXI-11 service, which is then accessible by popular test application languages. Note that VXI-11 is a protocol-defining spec that establishes how to control IEEE-488.2-compliant instruments over a TCP/IP-based packet network. TCP (the transport layer) and the Internet Protocol work together to guarantee error-free communication with the Model 8055.
Its name notwithstanding, the VXI-11 spec itself isn't limited to VXIbus systems. Indeed, the VXI-11 specification was part of a suite of specs developed in the 1990s when the VXIbus was created. For its part, VXI-11 describes how instruments or other devices can be connected to TCP/IP networks, with communications and programming similar to the techniques supported by GPIB IEEE-488.1 and IEEE-488.2 definitions. To simplify, the protocol supports ASCII-based communications between a controller and a piece of test gear, across a network.
Mapping RPCs
In operation, the 8055 maps VXI-11.3 and RPC (remote procedure call) requests into GPIB commands to ultimately control your IEEE-488 instrument. An application or client can call procedures in a remote application or device (a server) just like the remote procedures were being executed locally. The Model 8055 box and the GPIB instrument itself collectively morph into what amounts to a VXI-11.3-compatible instrument.
Especially significant is the fact that the Model 8055 makes it possible to run the GPIB instrument without a GPIB controller, as well as letting you include your instruments in LXI or Ethernet-based test systems. Because VXI-11 devices are IEEE-488.2 devices, all IEEE-488.2 protocol and format rules apply to the commands sent to a VXI-11 device. You can then program the device just as you would program a GPIB instrument. Return data isn't a response to a query, but rather an acknowledgement that the device received the message. Transmission or command errors are indicated by returned data. By the way, as alluded to above, the Model 8055 will operate in an LXl system, but it may need IVI drivers for LXI compatibility.
Easy Windows
It's a fair bet that most existing Windows programs that controlled the IEEE-488 instrument through a GPIB controller can be adapted for control through the Model 8055. If the application program was written with VISA (Virtual Instrument Software Architecture) calls, you can simply change the VISA Resource string to select a TCP/IP device.
As an example of versatility, National Instruments popular Measurement and Automation Explorer package would treat the Model 8055 and the GPIB test instrument just like any other VXI-11.3 instrument. Similarly, Agilent Connection Manager would see the 8055-instrument as a VXI-11.3 instrument.
The Mathworks MATLAB and other applications that use VISA can also control the combo. If your application was making direct GPIB calls, it will need to be changed to make VISA calls. Visual Basic, VB.NET, C, C++, and C# programs can also be used to control the Model 8055 and the instrument, using SICL (Standard Instrument Control Libraries), or VISA calls. If the companion GPIB instrument has an IVI driver, it can be integrated into a test program written for LXI instruments.
As briefly mentioned in the press release, the company ships the Model 8055 with a VXI-11 keyboard program. Designed for installation on Windows PCs, it gives you out-of-the-box control of VXI-11 instruments from your computer, without any programming. Your keyboard lets you interactively exercise the 8055 and the target instruments. You can also use this program to try device commands before deploying them in code.
Finally, the Model 8055 also supports Agilent VEE, NI LabVIEW, and other programs running under Windows or HP-UX, UNXI, Linux, SunOS, Apple OS X, and other operating systems. It doesn't require special drivers for each operating system. All in all, the Model 8055 shapes up as a low cost way to extend the utility of GPIB test equipment. In these times of economic belt tightening, it looks like a surefire way to give a new lease on life to older test equipment.
Data Sheet
|
|
|
|
|
