Figure 2-7: RS-232 interconnection of TMFs and PC (not for Probus)
The RS-485 is essentially a multidrop connection. It allows a maximum of 32
devices to be connected to a computer system. IBM-compatible PCs are not
equipped with RS-485 ports as standard. An RS-232 to RS-485 converter
or RS-485 interface board is therefore required to connect an RS-485 to a
standard PC. Figure 2-8 is an interconnection diagram showing two MFs
linked to an IBM-compatible PC, via RS-485 and RS-485 to RS-232 converter.
The RS-485 bus requires two resistors of 120, one at the end of the bus and
one at the beginning, near the converter depending on the convertor, the
resistor may already be installed internally in the converter. The RS-485 bus
also requires a daisy-chain network, meaning that the wires are connected as
showed in gure2-8.
Figure 2-8: RS-485 multidrop interconnection TMFs and PC
Section 2: Installation
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