Yaskawa CM012 DeviceNet Option Card - Manual (Page 74)

Troubleshooting 6-5
Network Wiring
1. † Connector Wiring „
The network cable wires are connected in the correct order.
„
All network wires are securely connected.
„
There are no short circuits between network wires or shield.
„
The network connector is securely inserted into the mating connector.
2. † Network Cable „
The number of DeviceNet nodes does not exceed 64 on any one network.
„
No drop line is longer than 6 m.
„
The total drop length is less than the allowable length for the network baud rate and cable
type.
„
The network trunk length does not exceed the allowable length for the network baud rate
and cable type.
„
Network cables are not close to high power or frequency cables.
3. † Terminating Resistors „
The terminating resistors are appropriately installed and are of the correct size and type.
„
Measure the DC resistance between CAN_L and CAN_H at the ends and middle of the
network. The measurement should be between 50 ohms and 70 ohms.
4. † Grounding „
Single point ground technology is used.
„
The network shield and drain wire are grounded at only one point, preferably in the center
of the network.
„
The 24VDC power supply common is grounded at the same point as the network shield and
drain wire.
„
Check for noise with an oscilloscope.
5. † 24VDC Power Supply
„
Turn on the 24VDC power supply and configure all nodes for their maximum current draw.
„
Measure the voltage between V+ and V- at the power supply and at each end of the
network. The voltage should not fall below 11VDC at any point on the network. If the
network contains powered devices (proximity sensors, photoelectric sensors, etc.) the
voltage should not fall below 20VDC.
„
The 24VDC power supply common is grounded at the single point ground.