Actisense USG-1-B-485, Руководство пользователя

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Page 7 © 2009 Active Research Limited
USG-1 connections
Figure 1 – Inside the USG-1 case
Figure 1 shows an internal view of the USG-1 Printed
Circuit Board (PCB). The USG-1 has screw-terminal
“Phoenix” type connectors with a pre-installed cable.
This cable should be sufficient for most installations. The
colour codes used for this cable are:
Wire colour Function
Shield / Screen ISO-Drive Ground
Blue ISO-Drive RS485 B/-
White ISO-Drive RS485 A/+
Black ISO-Drive RS485 B/-
Red ISO-Drive RS485 A/+
This cable also has a screen connection. This is not
connected inside the USG-1: in most instances, simply
connect this to ground at the instrument end, and this will
provide correct screening of the signals on the USG-1-485
data cable.
1/2. An RS485 bidirectional connection.
Two sets of screw-terminal Phoenix-style connectors
(1 &2 in figure 1) are provided to connect the RS485
network. These connectors are provided for use
when the customer needs to use their own cable.
The bottom set of three screw-terminal Phoenix-style
connectors provide a second set of connections to
the RS485 network, along with a reference to the
floating ground of the USG-1-485 driver circuitry to
use where required.
Both sets of connections provide connections: ‘ +/
A ’, ‘ -/B ‘. This allows the USG-1-485 to interface to
various different devices that require any combination
of these outputs. Both sets are connected in parallel
on the board. This allows a network to be created,
by allowing a connection in from the RS485 network,
and the second set used to connect to further devices
on the network.
Note: The connection marked “GND” on the
connection block 3 is not USB or PC ground, it
is connected to the isolated ground of the ISO-
Drive circuit. In most installations, this GND should
be left disconnected. It is only for use in special
circumstances where an RS485 3-terminal type
connection is required, and is reserved only for
specialist installations. No damage will be caused
by connecting to this GND in error, but it may result
in missing or corrupted data if it is used incorrectly.
Always follow the connection diagrams shown in this
manual to ensure correct operation.
3. A micro-connector to connect to the supplied
USB type A terminated cable.
This connector should not normally be removed:
it is installed at the factory and is not customer
serviceable.
4. An indicator LED - USB
This LED flashes when data is sent from or received
from the USB side of the USG-1. It can be clearly
seen through the USG-1’s translucent lid when the
case is closed.
5. An indicator LED - RS485
This LED flashes when data is sent from or received
from the RS485 side of the USG-1. It can be clearly
seen through the USG-1’s translucent lid when the
case is closed.
6. An echo-mode header
Connecting the supplied link between pins 1 and 2
sets the “echo” mode, which returns all data sent by
the PC. Connecting pins 2 and 3, sets the “no echo”,
mode, which is the factory default.
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