Oldham MX 43, Руководство пользователя

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26 MX43
User
manual
RS485 Transmission
General Topology of RS 485 Network
The digital modules are linked by 2 twisted cable pairs of 4 x 0.22 m² minimum,
type MPI-22A, nominal resistance of 120 Ohms. This cable carries the RS485 (A
and B) signal on one pair and the power supply of the modules (0–24 VDC)
connected to the line on the other pair. Shielding necessarily links all the modules
to the terminal block of MX43.
The + 24 VDC, 0V, A, B terminals are respectively connected to +24VDC, 0V, A,
B terminals of the other modules on the line and then to the connector of the
corresponding line on the central unit. The cable shielding must be connected to
the grounding rod of the MX43.
At the end of the busbar, the 120-Ohm end of line resistor (
EOL
RESISTOR/RESISTANCE F.D.L
) must be activated (whatever the last module).
No portion of the bare end of the terminal wires should be visible.
For protection against any electromagnetic disturbances, the data
as well as screen wires (or braids) must be cut as short as
possible.
042
Figure 14: Principle of connecting modules to a MX43 line.
An incorrect installation of the cables or cable glands can cause
measurement errors or a malfunctioning of the system.
Do not lay the cables close to equipment such as engines,
transformers, or lines generating important magnetic fields.
It is recommendable to always ensure a distinct separation
between these cables and the cables of other circuits.
Configuration of Communication
Module Address
All the digital modules on a line must be
identified by a unique address.
Switches 1 to 5 of the configuration block of
each module make it possible to establish an
address number (1 to 32) in binary mode.
In the illustration to the right, the address 9
(10010) has been defined.
The
Addressing Table
below lists the possible
combinations.
004
Figure 15: Switches of
address configuration.
MX43 line terminal
Terminal (detector,
module)
Earthing
terminal
MX43