2-11
2 Nomenclature and Installation
CJ-series PROFIBUS Slave Unit Operation Manual for NJ-series CPU Unit (W510)
2-3 N
etwork In
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all
ation
2
2-
3-3 PR
OF
IBUS Cable Conne
ctor
Installing the inductors applies to all devices on the network, and not only to the devices at both ends
of the bus cable.
Bus Cable Connector
The plug connector to be used on the CJ-series PROFIBUS-DP Slave Unit is
a 9-pin male sub-D type, preferably encased in metal and having a facility to
connect the shield of the cable to the case or to pin 1. The cable should be
connected to the receive / transmit lines, pin 3 (B-line) and pin 8 (A-line).
The use of special PROFIBUS-DP cable connectors, which are available
from several manufacturers, is highly recommended. Various models are
widely available, with or without the bus termination and inductors built-in. If
provided in the connector, the Bus termination can often be enabled or dis-
abled through a switch on the connector.
The special PROFIBUS DP cable connectors often provide a convenient way
of connecting the cables. The figure on the left, provides an example of such
a bus cable connector.
A standard 9-pin sub-D plug can only be used if the PROFIBUS-DP Slave
Unit is not at the start or the end of a bus segment, or on a stub line at a baud
rate of 500 kbps or less.
The two PROFIBUS data lines are designated A and B. There are no regula-
tions on which cable core color should be connected to which of the two data
terminals on each PROFIBUS device; the sole requirement is to ensure that
the same core color is connected to the same terminal (A or B) for all devices
throughout the entire system (across all devices and bus segments). The
PROFIBUS Organization recommends the following rule for data line color
codes: PROFIBUS cables in general will use the colors red and green for the
data lines, with the following assignment:
•
Data cable wire A - green
•
Data cable wire B - red
This rule applies to both the incoming and the outgoing data lines.
Bus Cable Connector
To ensure electro-magnetic compatibility (EMC), the shield of the cable
should be connected to the metal case of the plug connector.
If the Unit is installed in a control cabinet, the bus cable shield should be
brought into physical contact with a grounding rail using a grounding clamp or
similar device. The cable shield should continue in the cabinet right up to the
PROFIBUS device.
Ensure that the CPU and the control panel in which it is mounted have the
same ground potential by providing a large-area metallic contact to ground,
e.g. galvanized steel to ensure a good electrical connection. Grounding rails
should not be attached to painted surfaces.
2-3-3
PROFIBUS Cable Connector
2-3-4
Shielding Precautions
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