Epson RC620 Manual page 169

♦ Causes of Error
Possible Cause
 Voltage drop of
communications
power supply
 Disconnected
terminating resistors
 Cable disconnection
 Disconnected
connector
 Disconnected signal
wire
 Loose connector
 Loose signal wire
 All slaves power
OFF
 Master unit
configuration
RC620 Option Fieldbus I/O Rev.8
Examination Method
Measure voltage of
communications power supply at
the master unit.
→ Normal: 11V or more between
V+ and V-
 If the voltage is 11 to 14 V, the
master unit is a possible cause.
Fix the problem on it.
(1) Check that terminating
resistors are connected to
both ends of the network.
(2) Measure resistance between
signal wires with
communications power
supply OFF.
→ Normal: 50 to 70 Ω
 Measuring point: Connection
of the master
 For details, refer to the section
4.1.3.1 Connection Problem.
Check for the connection of
connectors and signal wires.
→ The connectors and signal
wires should be firmly
connected.
 Checkpoint: Between the
master and its slaves
 For details, refer to the section
4.1.3.2 Loose Connector and
Signal Wire.
Measure the power voltage of the
slaves.
(It should be within the range of
sufficient voltage for slave
operation.)
(1) Start applicomIO Console
application and check that
the configuration has no
difference with the network
condition.
(2) Check that the configuration
data were written in flash.
 For details, refer to the section
4.1.3.6 EPSON RC+ Master
Configuration.
4. Troubleshooting (DeviceNet)
Countermeasure
Check voltage of the 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 120 Ω.
Connect the connectors
and signal wires again.
Supply power to the slaves.
Change the configuration.
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