Procedures For Examining Possible Causes - Epson RC620 Manual

4. Troubleshooting (DeviceNet)

4.1.3 Procedures for Examining Possible Causes

4.1.3.1 Connection Problem (Disconnected Terminating Resistors, Cable
(1) Ensure that two terminating resistors are connected to both ends of the network.
(2) Turn OFF the communications power supply.
(3) Measure resistance between CAN_H and CAN_L wires of the absent slave using the
(4) How to find the trouble point:
160
Disconnection, Disconnected Connector, and Disconnected Signal Wire)
tester.
Tester
Ω
Red (CAN H)
Resistance
0 Ω
Short circuit
Under 50 Ω
Three or more terminating resistors on one network
50 to 70 Ω
Normal
70 to 120 Ω
Error (cable disconnection or disconnected signal wire on the
trunk line)
Over 120 Ω
Error (cable disconnection or disconnected signal wire on drop
line or trunk line → Both CAN_H and CAN_L)
- Remove the terminating resistor on one end of the network.
(The resistance at the point where the terminating resistor is connected is 120Ω.)
- Measure resistance at branch taps of all units.
- The trouble point is where resistance changes from 120Ω.
- After finding the trouble point, verify the connector and cable conditions.
Measure resistance between signal wires with tester.
Blue (CAN L)
Determination
RC620 Option Fieldbus I/O Rev.8