Epson RC90 Manual page 313

♦ Causes of Error
Possible Cause
 Electrical surges of
device power supply
 Disconnected
terminating resistors
 Cable disconnection
 Disconnected
connector
 Disconnected signal
wire
 Loose connector
 Loose signal wire
 Broken unit
RC700 / RC90 Option Fieldbus I/O Rev.14
Examination Method
Measure voltage of the device
power supply at the trouble
unit.
→ It should be within the range
of sufficient voltage for
device operation.
(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.
4. Troubleshooting (PROFIBUS DP)
Countermeasure
Check voltage of the device
power supply.
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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