Omega A1000 Series, User Manual

A1000 &  A2000 USERS MANUAL  4

GENERAL DESCRIPTION
The  A1000  and  A2000  series  converter  boxes  convert  RS-232
communications signal levels to the correct electrical signals required by
RS-485. The RS-485 communications standard is recommended when
many modules, or other addressable devices, must be connected to a
host computer over long distances. The A1000 and A2000 converters
allow communications bus lengths up to 4,000 meters and baud rates up
to 115K baud using one twisted pair of wires.

The RS-485 communications standard is half-duplex, therefore data can
be transmitted in only one direction at a time. The A1000 and A2000
automatically  control  the  bus  direction  without  external  handshaking
signals from the host. Therefore, host software written for RS-232 may be
used without modification. RS-485 bus control is completely transparent
to the user.

The A1000 and A2000 can also operate as RS-485 repeaters. Repeaters
are required to extend communications bus lengths or allow more than
32  RS-485  devices  to  be  connected  to  a  communications  bus.  A
repeater  simply  reamplifies,  or  boosts,  existing  RS-485  signals
transmitted over long distances.

The A1000 converter boxes are powered by either 115Vac or 230Vac
and contain an in24-volt 1A power supply for powering modules.
The  A1000  power  supply  is  protected  against  overloads  and  short
circuits. The internal power  supply  may  be  used  to  power  accessory
circuits such  as  relays  or  4-20mA  transmitters.  The  A2000  converter
boxes operate on a wide range of power supply input v10  to
+30Vdc unregulated.