User`s manual

Western Reserve Controls, Inc. 1782-JDO User’s Manual
PRELIMINARY
17
Figure 4-2 DeviceNet cable connector
4.4.3 RS485 Network Termination (1782-JDO-2)
It is common practice to terminate an RS485 network system at each end of the serial
cable to eliminate electrical reflections. An appropriate value for the terminating resistor
typically is:
•100-120 ohm, depending upon the characteristic impedance of the cable used
o121 ohms (same value as the DeviceNet terminator) is a standard resistor value
that may be used in many cases
•1% metal film
•1/4 Watt
Correct cable termination is the responsibility of the user. The 1782-JDO-2 does not include
an internal terminating resistor.