Epson RC620 Manual page 199

♦ Causes of Error
Possible Cause
 Disconnected
terminating resistors
 Cable disconnection
 Disconnected
connector
 Disconnected signal
wire
 Loose connector
 Loose signal wire
 Broken unit
 No cause is
identified.
RC620 Option Fieldbus I/O Rev.8
Examination Method
(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
 Measuring point: Connection of
the trouble unit
 For details, refer to the section
4.2.3.1 Connection Problem.
Check for the connection of
connectors and signal wires.
→The connectors and signal wires
should be firmly connected.
 Checkpoint: all stations and all
branch taps
 For details, refer to the section
4.2.3.2 Loose Connector and
Signal Wire.
Replace the trouble unit with a new
one.
→Verify whether the problem is
fixed.
Identify the trouble point by
dividing the network.
→ For details, refer to the section
4.2.3.4 Broken Unit Examination.
4. Troubleshooting (PROFIBUS DP)
Countermeasure
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.
Connect the connectors
and signal wires again.
Replace the unit with a
new one.
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