Connect-and-View™ trigger simplicity for
hands-off operation
Shielded test leads for oscilloscope,
resistance and continuity measurements
Industrial Networks bus
health testing
Measure harmonics and power, VA, VAR, W, PF
Up to seven hours battery operation
600 V CAT III safety certified
Optically isolated RS-232 interface
Rugged compact case
Bus Health Tester
Resistance and Capacitance measurements.
Troubleshooting a network segment starts with checking connectivity,
measuring the cable impedance making sure it is not open or shorted.
Cable impedance is dependant on network type, for example, Foundation
Fieldbus uses a 120 Ohm cable terminated at either end of the segment
with 120 Ohms. Also, check capacitance, making sure it is within
specification. A good cable is essential for proper electrical signal
performance.
Network signal electrical performance.
Checking electrical signal performance requires measuring key parameters
of the network signal. The 125 includes a Bus Health test mode that is
designed to trigger on and capture network signal waveforms. Select a
bus type, the ScopeMeter Bus Health mode then runs algorithms to measure
key signal parameters like bias voltages, signal low, high and
peak-to-peak levels. The bus health mode also measures distortion or
signal jitter determining overall signal quality.
Verify signaling meets specification.
The signal parameter measurements are compared to the industry
specification, a low and high limit defined by the standard is used to
determine if these key parameters are within specification. Display
icons are used to clearly indicate which parameters are outside of the
industry specification.
Fluctuating or incorrect bias voltages is indicative of grounding or
termination issues, while low signal level measurements could mean there
is excessive attenuation caused by too long cable runs, too many devices
on one segment or simply incorrect network termination. Signal
distortion like overshoot is a sign of reflections typically caused by
cable imperfections or failing connectors.
Inspecting the signaling for disturbances is simplified with the “eye
pattern” display mode. The clearer the center “eye” of the signal
display the less distortion and disturbances on the signal. Phase noise
and jitter are typical digital signal distortion caused by device
receiver transmitter circuits. External electrical interference from
high-energy sources such as lighting systems and heavy-duty machinery
can be detected by inspecting the eye pattern.
Electrical interference like noise, static discharge and transients can
cause network devices to reset, monitoring a segment can capture these
events thereby helping to isolate their source.
Once the cabling and signaling parameters are eliminated, network
protocol diagnostic tools are used to verify digital protocol
performance.
Eliminating cabling and signal quality issues are two critical steps to
isolating network performance issues. The Fluke 125 ScopeMeter includes
measurement functions and algorithms to verify the integrity of network
digital signaling.