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ULM.0.01.000RE_10_08_20
Fig. 6.5 RS-485 line “Star” laying method
Low transmission rate of 9600 bps used in level transmitter provides good interfer-
ence immunity of communications line and allows application of various cable lay-
ing options including so-called “star” method shown in Fig. 6.5. User can choose
the suitable laying option based on cable laying ease and length minimization con-
siderations. Generally, such type line construction does not require installation of
tracking resistors.
In the long and branched lines, few communication errors could occur. These com-
munication errors do not cause the unreliable level data acquisition, since the Mod-
bus data communications protocol used in level transmitter contains check sum
computation allowing detection of corrupted data. Such data are ignored.
