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Firewire Ready for Instrument and Control Applications
By Gary Sakmar
Keithley Instruments, Inc.
The 1394 Trade Association (1394TA) has published two new data
communication protocols that facilitate the use of IEEE-1394 (Firewire) for
measurement and control applications. The introduction of these protocols opens
up new possibilities for system developers by providing efficient, high-speed
communication between PC controllers and electronic instrumentation and
control devices.
There are two major advantages of connecting measurement and control devices
using industry standard I/O, such as that defined by Firewire:
1. Cost -- Standard I/O connectors and cables are less expensive than those
using proprietary designs, which usually are produced in lower volumes.
2. Ease of use -- You simply plug standard, familiar cables into connectors that
already exist on the PC. In Firewire's case, there is no need open up the
computer to install a host bus adapter and you do not have to deal with hardware
or software configurations for such an adapter.
Within the framework of the general Firewire specification, there is the
opportunity for data communication rates up to 400MHz, with 1GHz planned for
the near future. However, until now, system designers were in a quandary on
how best to implement use of Firewire. What they needed was a lightweight
protocol that would make it easy to implement these high-speed
communications.
The Industrial Instrument and Control Working Group of the1394TA, which
consisted of members from Keithley Instruments, 3A International, Agilent and
National Instruments, solved this problem by sponsoring development of two
protocols that facilitate use of IEEE-1394 in measurement and control
applications. Protocol 1394TA IICP-1.0 details the basic methodology for
asynchronous communications to electronic instrumentation and control devices.
Protocol 1394TA IICP488-1.0 describes use of the first protocol to communicate
IEEE-488.1 and -488.2 messages and command/control sequences on a
Firewire bus. This facilitates the use of GPIB (SCPI) commands with Firewire.
(These protocols can be downloaded as PDF files from the 1394TA web site at
www.1394TA.org/Download/Technology/Specifications/iicp1.0.pdf and
www.1394TA.org/Download/Technology/Specifications/iicp4881.0.pdf.
The 1394 serial bus interface is already becoming a standard offering on some
PCs, and many more manufacturers plan on providing it to meet I/O needs for
consumer electronics. Instrument and control system developers are now taking
greater interest in Firewire, not only because of its bandwidth, but also because
of the following advantages: