ADLINK ND-6067 - Manual (Page 17)

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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.
The ND-6530 is the USB to RS-485/RS-422/RS-232 converter, and it is used to
build the USB signal into RS-485/RS-422/RS-232 signal.
The ND-6531 is an addressable RS-485/RS-422 to RS-232 converter, it allows
the RS-232 devices easily link to Host by the RS-485/422 bus.
Figure 1-1 Simple Topology
Host
NuDAM Modules
RS-232
RS-485 bus
ND-6520/ND-6530
Terminator
ND-6531