User`s manual

Western Reserve Controls, Inc. 1782-JDC User’s Manual
11
Table 4-4 Maximum Network Cable Lengths
Trunk Line Length Drop Length
Maximum Distance Maximum Cumulative
Baud Rate Meters Feet Meters Feet Meters Feet
125k baud 500 m 1640 ft 6 m 20 ft 156 m 512 ft.
250k baud 250 m 820 ft 6 m 20 ft 78 m 256 ft.
500k baud 100 m 328 ft 6 m 20 ft 39 m 128 ft.
4.4.1 Network Termination
A DeviceNet system must be terminated at each end of the trunk line. The host controller and
the last JDC or other DeviceNet device on the network must always be terminated to eliminate
reflections, even if only two nodes are present. The DeviceNet specifications for the terminating
resistor are:
• 121 ohm
• 1% metal film
• 1/4 Watt
An appropriate terminating resistor, WRC part number RM121DN, may be purchased from WRC.
IMPORTANT:
Per the DeviceNet spec -- do not terminate devices on drop lines.