System Expansion - Pepperl+Fuchs LB Series Manual

LB Remote I/O System
Installation
Field Wiring
Depending on the application, the shielding of the wiring must be grounded at one point or at
both ends. If possible, avoid grounding at both ends to prevent ground loops and ensure the
shielding is not used as a return line.
Sound results can be obtained with grounding at one end of the cable if the cable is laid on a
grounded metal cable support. The metal frame in the immediate vicinity of the conductor
ensures that only small areas are exposed to the field, so that interference is largely reduced.
Digital inputs are normally controlled by NAMUR proximity switches with a low-impedance
signal. In this case, interfering signals have a far lower impact than in circuits containing open
switches that do not have an additional resistor circuit. For this reason, do not connect digital
inputs to exposed wiring.
The analog signals of resistive sensors or thermocouples are particularly susceptible to
interference. Signal converters have built-in filters to reduce this interference. The filters can be
switched on if fluctuations in the measuring signal cannot be reduced sufficiently by other
means. For more information, refer to the software manual for the com unit used.
Fieldbus Connection
Ground the shielding of the fieldbus cable at both ends. Grounding at one end is sufficient if the
fieldbus cable is laid on a grounded metal cable support.
Eliminating Interference
The following measures can improve power.
1. Fit line filters in power supply lines.
Please make sure that supply cables leading to line filters are laid separately from other ca-
bles to ensure that any filtered interference is not picked up again.
2. Fit surge protection filters in signal lines.
3. Change to galvanically isolated circuits.
3.16

System Expansion

Adding I/O Modules
By adding an I/O-module, input or output data will be transferred to a slot that was previously
empty. To do this, the configuration of the com unit must be adapted. Changes to the
configuration of the com unit usually result in the function being interrupted due to a fieldbus
restart.
To avoid this, you can activate Hot Configuration in Run (HCiR) in the com unit. If HCiR is
active, a new configuration can be transferred to the com unit in the form of a passive data
record. In this way, the master still has access to the old configuration in its existing form. As
soon as the new configuration in the master matches the new configuration in the com unit, the
new configuration in the com unit is activated and the old configuration is deleted. For more
information, refer to the software manual for the com unit used.
Alternatively, you can use the Unicom com unit LB8109*. Using the Unicom com unit, you can
configure the slots on the backplane in such a way that they can later be used with different I/O
modules. For more information, refer to the software manual for Unicom com unit LB8109*.
Extending the Fieldbus
In order to extend the fieldbus cable, the terminator must be removed. In this case, operation
can only be maintained using a redundant system.
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