CIRCUTOR computer SMART III-Fast Series - Manual (Page 58)

4�9�-RS-485COMMUNICATIONS
Computer SMART III FASTunitshaveanRS-485serialcommunicationoutputwiththeMod-
bus RTU ®communicationsprotocol
4�9�1� CONNECTIONS
TheRS-485cableshouldbewiredwithatwistedpaircablewithmeshshield(minimum3
wires),withamaximumdistancebetweenthe Computer SMART III FASTandthemasterunit
of1,200metres�
Amaximumof32 Computer SMART III FASTunitscanbeconnectedtothisbus�
UseanintelligentRS-232toRS-485networkprotocolconverter(M54020intelligentconverter)
toestablishthecommunicationswiththemasterunit�Thisconverterdoesawaywiththeneed
forthePin7connectionontheRS-485side�
B ( - )
A ( + )
S
A( + )
B( - )
S
RS-232 / USB / Ethernet / Profibus ...
PC
RS-485
RS-485
RS-232
USB
Ethernet
Profibus
...
Figure 16: RS-485 Connection diagram�
58
Computer SMART III FAST
Instruction Manual