Software Calms Machine Jitters
Electronic commands passed from machine to machine over data networks drive many modern production lines.
But timing irregularities
in the signals from even
one machine a difference
of only a tenth of a second
can result in havoc on
the plant floor. These timing
glitches, called “cyclic jitters,”
can make machines jump or
shake, damaging products,
even shutting down entire
assembly lines. Fortunately,
software recently developed
by engineers at the National
Institute of Standards and
Technology (NIST) should
help calm those jitters.
NIST’s EtherNet/Industrial Protocol
software tool helps manufacturers
anticipate how machines
will perform. And data from the
tool can improve performance.
Different vendors define the
performance of network devices
in various ways. These differences
make it difficult for manufacturers
and plant engineers to compare
high-speed data transmission
of similar devices. To determine
how performance characteristics
relate requires time-consuming searches through vendor manuals
or spending hours contacting
vendors. Although standardized
tests can indicate how well devices
conform to communication specifications,
until now manufacturers
couldn’t be sure how well the
devices worked under normal or
heavy transmission conditions on
the factory floor.
The software collects device information
from the user, generates
test scripts based on that information, analyses performance data,
and reports results to the user. The
software provides transmission data
for three conditions: no background
traffic, small background traffic, and
over 240 devices on the network.
NIST began the project at the
urging of U.S. Council for Automotive
Research (USCAR) Plant Floor
Controllers Task Force and developed
the program with the Open
DeviceNet Vendor Assoc. ODVA,
a vendor organization that maintains
the DeviceNet and EtherNet/
IP standards used extensively by the
U.S. automotive industry, plans to
begin using the test tool later this
year.