4. Troubleshooting (PROFIBUS DP)
♦ Causes of Error
Possible Cause Examination Method Countermeasure
{ Electrical surges of
device power supply
Measure voltage of device
power supply at the trouble
unit.
→ It should be within the range
of sufficient voltage for
device operation.
Check voltage of the device
power supply.
{ Disconnected
terminating resistors
{ Cable disconnection
{ Disconnected
connector
{ Disconnected signal
wire
(1) Check that terminating
resistors are connected to
both ends of the network.
(2) Measure resistance
between signal wires with
device power supply OFF.
→ Normal: 100 to 120 Ω
z Measuring point: Connection
of the trouble unit
z For detail, refer to the section
4.2.3.1 Connection Problem.
Fix the problem.
How to find the trouble
point:
Remove the terminating
resistor on one end of the
network. The trouble point
is where resistance changes
from 220 Ω.
{ Loose connector
{ Loose signal wire
Check for the connection of
connectors and signal wires.
→ The connectors and signal
wires should be firmly
connected.
z Checkpoint: all stations and
all branch taps
z For details, refer to the
section 4.2.3.2 Loose
Connector and Signal Wire.
Connect the connectors and
signal wires again.
{ Broken unit Replace the trouble unit with a
new one.
→ Verify whether the problem
is fixed.
Replace the unit with a new
one.
122 Fieldbus I/O Rev.6