Studer Innotec SA
Xcom-485i
8
User manual
5.2
C
ABLE BETWEEN
X
COM
-485
I AND THIRD PARTY DEVICE
Most communication devices provide a specific connector
and pin assignment. A specific cable having on one side an
RJ-45 connector and on the other side the third-party devices
connector is required. This cable is either supplied by the
manufacturer or must be crafted by the installer.
The Xcom-485i package provides 2 cables with RJ-45
connectors on both ends. One of the two can be used to
craft the proper cable.
5.3
S
ELECTION OF THE
PIN
ASSIGNMENT OF THE
RS-485
BUS CONNECTION
Any Modbus communication signal can be assigned to any pin of the RJ-45 connector by using the
jumper array (1) as shown in Figure 1: Electronic board inside the Xcom-485.
The grey squares in the jumper array show the pin number of RJ-45 connector which can be
connected to any signal of the communication interface (GND, D+, D-) using the jumpers. By
default, no connexion is done inside the module, so you have to open it and configure it manually.
The EIA/TIA-
485 standard uses A/A’ and B/B’ signal names for data signals. However, this naming is
subject to interpretation, as most of the IC manufacturers uses it in a wrong way. In order to avoid
this confusion, we use D+ (for Tx+/Rx+) and D- (for Tx-/Rx-) as they are easier to understand.
Here is an example of how the jumper array could be configured, depending on your cable.
Jumper array
5.4
M
OUNTING
The Xcom-485i can be mounted directly on any support by means of the supplied fixing plate, on
a smooth surface with double-side adhesive or on DIN rail using the DIN rail clips (part of the
Xcom-485i communication set).
4 = D-
5 = D+
8 = GND
If the data lines D+ and D- are crossed or wrongly connected, it will not destroy the device
but the communication will not work. So in case of communication issue, it can be a good
idea to cross D+ and D-.
