4 Setting Up
4.5 Installation
24
Version 2.4 04/07
4.5.4 Connecting the electric RS 485 bus
lines
The modules are fitted with an RS 485 electrical port.
This is a 9-pin Sub-D socket with a screw lock (inside
thread UNC 4-40).
The pin assignment complies with the PROFIBUS stan-
dard. At Pin 6 there is a short circuit-proof 5 V output for
supplying external pull-up/pull-down resistors.
As opposed to the 24V power supply, the RS 485 bus
lines RxD/TxD–N and RxD/TxD–P are indirect-coupled
(functional separation) within SELV restrictions.
The RS 485 interface is electrically connected to the
housing.
Fig. 11: Electrical port – assignment of Sub-D sockets
9 / n.c.
8 / RxD/TxD –N
7 / n.c.
6 / + 5 V Output
Ground
n.c.
RxD/TxD –P
Ground
PE
Shield
/ 5
/ 4
/ 3
/ 2
/ 1
䊳
Only use shielded and twisted-pair wiring as a RS 485
bus line.
䊳
Use a PROFIBUS bus connector plug to connect the
RS 485 bus segment.
Notes:
- If the module is at the beginning or end of a bus
segment, this connector must have an activated
bus terminal resistor combination.
- Ensure that the bus segment connected to the
RS 485 interface is terminated at both ends.
- Only use a connecting cable which is terminated at
both ends to connect a single device.
䊳
All PROFIBUS bus connector plugs in a network must
be securely screwed onto the RS 485 interfaces.
䊳
Attaching or removing the bus connector plugs,
inadequately attached bus connector plugs or loose
bus wires within the plug can lead to malfunctions in
the optical and electrical networks.
䊳
Attach or remove the RS 485 bus connector plug
quickly and without twisting them.
䊳
Remove the RS 485 bus line from the OZD Profi if a
device is not connected to the other end, or there is
an OZD Profi which has been disconnected from the
power supply. The open line otherwise acts as an
antenna and can cause interference.
䊳
When connecting a RS 485 bus line to the OZD Profi
12M … in an active network, keep to the following
sequence in order to avoid interference:
1. Place the RS 485 bus connector plug onto the
device which is to be connected (e.g. to a program-
ming device) and screw it on tightly.
2. Attach the RS 485 bus connector plug to the
OZD Profi 12M … quickly and without twisting the
connector, and screw it on tightly.
Proceed in the reverse order when removing a device
from the network.
Warning !
Do not connect any bus lines which have been
partially or totally laid outside of buildings. Otherwise
lightning strikes in the vicinity of the cable could destroy
the module. Use optical fiber lines for bus connections
which lead out of a building!!
