ADLINK Technology NuDAM ND-6510, User Manual, Page: 8 / 47

1-4 Introduction
•
NuDAM-6060 : 4-channel Relay Output & Digital Input Module
•
NuDAM-6063 : 8-channel Relay Output Module
•
NuDAM-6080 : Counter/Frequency Input Module
1.4 EIA RS-485 Standard
The EIA RS-485 interface is a communication standard
developed for multi-dropped systems that can communicate at
high rate over long distance. The standard RS-485 can operate at
speed up to 10 M bps over cable length up to 4000 feet.
The RS-485 interface can support up to 32 drivers / receivers on
the same line. This allows actual networking applications on a
parity line system (sometimes called multi-drop).
The RS-485 uses differential transmission on a balance line. Its
easy wiring make it popular to use in industrial applications.
1.5 RS-485 on NuDAM
The NuDAM improves the RS-485 capability for minimizing the
user‘s cost. On each NuDAM module, a half-duplex RS-485
transceiver is used to communicate with other modules. A single
twisted pair of wires, which provides standard differential
transmission, is used to transmit and receive data between
modules. The high input impedance of each NuDAM receiver
allows up to
128 NuDAM modules on the same RS-485 bus
without using a signal repeater.
The maximum transfer rate of NuDAM is 115.2Kbps which is
lower than the maximum speed of the RS-485 standard. The
slew-rate limiter on every RS-485 transceiver of NuDAM is very
useful for transmitting error-free data, minimizing EMI, and
reducing reflections caused by improperly terminated cables.
The NuDAM on a network may not use the same power supply.
Therefore, the voltage difference between ground of the modules
may exist.