iSMA CONTROLLI Control Point User Manual page 13

Control Point Hardware User Manual
4.6.2 RS485 Network Termination
Transmission line effects often present a problem for data communication networks.
These problems include reflections and signal attenuation. To eliminate the presence of
reflections of signal from the end of the cable, the cable must be terminated at both ends
with a resistor across the line adequate to its characteristic impedance. Both ends must
be terminated since the propagation is bidirectional. In case of an RS485 twisted pair
cable this termination is typically 120 Ω.
Note: A termination resistor can be added with a third switch on the DIP switch on the
back of the panel:
• Off: termination resistor disconnected (default);
• On: termination resistor added.
4.6.3 USB Connection
The USB port is used to communicate with product software, such as the iSMA
Configurator or FCU Updater, for configuration and firmware updates. The USB port
provides 5 V DC power supply.
4.7 DIP Switch
The Control Point panel is equipped with a 3-position DIP switch. Each of three sections
has a separate function:
• the first switch allows for restoring default settings;
• the second switch allows for selecting a communication protocol;
Figure 10. RS485 connection
Figure 11. USB port
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