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3. Connecting to the RS485 bus.
3.1 System structure in the RS485 bus.
Use a twisted-pair cable as a transmission wire of the bus. The bus shall be of a ”point-to-point” topology,
the ”star” type of topology is to be avoided. If the bus is of a significant length it is recommended to use a shielded
cable that will prevent from errors during communication and lowers the system’s susceptibility to noise and
emission of radio frequency interference. It is also advisable to mount termination resistors at the ends of the bus.
Their resistance ought to be comparable to the impedance specific for the lead in use, i.e. 120 Ohm.
Shown below is a block diagram of an RS485 bus connected to a PSU network of PSBEN series.
Fig. 3. A block diagram of power supplies of PSBEN series connected to the RS485 bus.
The connection with the RS485 bus is through the “RS485” connector. Connect the wires of the RS485
bus to the A+, B- terminals of the connector. They are assigned in the same way and the connection is identical to
the rest of devices (A+ to A+, B- to B-).
3.2 Connecting the interface to the bus.
1) Connect the RS485 wire to the RS485 connector of the interface. Take notice of the A+, B- wires so that
they are connected in the same manner as in other devices, i.e. A+ to A+, B- to B-. In the case of shielded
wires, the shield is to be connected to the SG signal ground terminals.
2) Optionally, mount the 120 Ohm termination resistors at the end of the RS485 bus.
3) Connect the interface to the computer via a USB wire.
4) Run the PowerSecurity program.
Download the “PowerSecurity” program from the following page:
http://www.pulsar.pl/pl/pliki/PowerSecurity.exe
5) From the menu bar choose: Power Supplies > New Power Supply. There will appear a window of
Connection Settings in which all settings are to be adjusted.