ADLINK Technology NuDAM ND-6510, User Manual, Page: 9 / 47

Introduction 1-5
Excessive output current and power dissipation caused by faults
or by bus contention are prevented by the current limiter and the
thermal shutdown circuitry inside the NuDAM.
1.6 NuDAM RS-485 Network Configurations
NuDAM-6000 series is designed under RS-485 multi-drop network
architecture. Up to 256 NuDAM modules can be controlled in a
multi-drop network. The limit of 256 is due to command code.
The network can be connected by simple topology (Figure 1-1) or
branch topology (Figure 1-2) or free topology (Figure 1-3).
The ND-6520 and ND-6510 are the two basic communication
modules to construct a RS-485 network. The ND-6520 is a RS-
232 to RS-485/RS-422 converter. The ND-6520 is used to build a
RS-485 port for the host computer by converting standard RS-232
signal into RS-485 signal.
The ND-6510 is the RS-485 signal repeater which is used to
extend or to lengthen the network distance. A NuDAM bus can
connect up to 256 modules, each segment is up to 128 modules.
Whenever the numbers of the modules excess 128, the repeater
should be used. In addition, the length of a standard RS-485 bus
is up to 4000 feet, the repeater should be used whenever the
length of a signal bus is more than 4000 feet.
Figure 1-1 Simple Topology
Host
ND-6520
RS-232/RS-485
Converter
NuDAM Modules
RS-232
RS-485 bus
ND-6520
RS-232 to RS-485/RS-422
Converter
Terminator