AH 5 00 Mo d u le Ma n ua l1 0 - 1 2Product picture Type FunctionTAP-CB01 TAP-CB01: DeviceNet trunk cableTAP-CB02 TAP-CB02: DeviceNet drop cable10.3.4 Choice and Purpose of a DeviceNet Terminal Resistor Choice of a DeviceNet Terminal ResistorA DeviceNet network needs to connect a terminal resistor of 121 ohm at both ends of the trunkcable respectively.The thick cable represents the main cable and the thin cable represents the sub-cable. Purpose of a DeviceNet Terminal ResistorThe terminal resistor is used for eliminating the signal reflection in the communication cable.All signal transmission cables have the characteristic impedance. The characteristic impedanceof Delta DeviceNet communication cable is about 121 ohm.When being transmitted to the end of the communication cable, because the impedance of theend is different from the characteristic impedance, the signal will be reflected, which willinterfere with the new signal and the signal wave form distortion will happen.The phenomenon of the signal wave form distortion is not obvious in the short-distancetransmission. But the wave form distortion will become severe with the increasingcommunication cable. Therefore, the two ends of the trunk cable must be installed with theterminal resistors respectively. Installation Position of a Terminal ResistorThe DeviceNet communication cable consists of five wires such as red wire, blue wire, whitewire, black wire and shielded wire as below.
