
Section 5.0 Installation Guidelines
HGA IOM
46
Serial Cable Termination Setup
Note:
The serial cable termination configuration for the HGA units are setup during assembly and test
of the unit. For new installations, the end user does not need to manually configure the serial cable
termination DIP switches on the power converters. These instructions only need to be followed if a
new power converter is being installed for repair.
In the HGA Active Filter, the serial communications cable between the Communications Interface
PCB and the Power Converters are implemented with RS-485 differential transceivers. These
differential transceivers are very robust in noisy industrial environments, if the serial
communication bus is properly configured with a termination resistor at each end of the
communications cable.
In the HGA Active Filter, the Communications Interface PCB is one end point of the serial
communications bus and has a built-in bus termination resistor that is always in circuit.
The other end point of the serial communications cable will be at one of the active filter power
converters. The power converter at the end of the communications cable should be configured with
the bus termination resistor in circuit or ON. The bus termination resistor ON/OFF DIP switch is
located near the J25 serial cable header (reference figure below).
Figure 22: Power Converter PCB Serial Cable Termination Resistor ON/OFF Switch.
For single power converter systems (480 V 50A, 100A, 150A, 200A, 250A, 300A, 350A and 600
V 39A, 78A, 150A, 185A), the bus termination resistor DIP switch should always be set to on. For
systems with two or more power converters (480 V 300A, 400A, 500A, 600A, 700A and 600 V
220A, 370A), only the bus termination resistor DIP switch of the power converter at the end of the
serial cable should be set on. For multi power converter systems additional power converters
located in the middle of the serial communication cable should have their bus termination
resistors out of circuit or OFF (reference Figure 22).
A piece of thin, adhesive tape will be covering the bus termination switch. This tape is used to
keep the conformal PCB sealant out of the switch mechanism during PCB assembly. This
covering will need to be removed in order to change the switch ON/OFF position.