Western Reserve Controls 1782-JDO Manuel d'utilisateur télécharger pdf (Page 18)

Western Reserve Controls, Inc. 1782-JDO User’s Manual

PRELIMINARY

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.

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Western Reserve Controls 1782-JDO Manuel d'utilisateur Page 18