Epson RC620 Manual page 171

♦ Process Flowchart
Check for cable laying.
Check that
terminating resistors
are connected.
Normal
Turn OFF communications power supply.
Measure resistance
with tester.
50 to 70 Ω
Normal
See 4.1.3.2.
Approx.
120
RC620 Option Fieldbus I/O Rev.8
Problem exists.
(Add terminating resistors.)
Out of 50 to 70 Ω (Error)
Resistance: over 70 Ω
Yes
Remove one terminating
resistor on either side.
Measure
Ω resistance at
connectors and
branch taps with
tester.
Other
Find the trouble point.
(1) Unconnected or loose connector
(2) Cable disconnection, etc.
4. Troubleshooting (DeviceNet)
No
Resistance: under 50 Ω
Ω
10 to 50
Check for connection
with terminating resistors
and branch taps.
(1) Three or more
terminating resistors
(2) Wrong terminating
resistors, etc.
Under 10 Ω
Check for short
circuit between
signal wires.
Short circuit
between signal wires
161