Termination
Termination
Termination
Termination
Termination
: Terminate the end devices on the RS-485
time data bus. For a one-way bus installation (as shown
in Figure 2-6), terminate the last device on the bus. In a
split bus installation (Figure 2-7) terminate the devices
installed on the extreme ends of the bus.
The TimeView 400 includes a built-in termination switch
that places a 120-ohm termination resistor across the RS-
485 line. Place DIP switch number 10 in the ON position
when the TimeView 400 is located at the end of the time
data bus.
Connection method
Connection method
Connection method
Connection method
Connection method
: The RS-485 transmission line must
be connected in a daisy-chain configuration as shown in
Figures 2-6 and 2-7. A branched or star configuration is
not recommended.
Taps into the main transmission line (stubs) should be
kept as short as possible. Long stub lengths affect the bus
impedance and capacitive loading that could result in
reflections and signal distortion.
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: Each NetClock or TimeBridge RS-485 output
can drive up to 32 RS-485 devices, including the
Spectracom products described below:
The Model 8175 TimeView 230, is a display
clock with 2.3-inch high green LED digits.
The TimeView 230 terminal block input
connects directly to the RS-485 data bus.
The Spectracom Model 8179T TimeTap® is
an RS-485 to RS-232 converter. The Model
8179T has a DB9 RS-232 interface which
receives operational power from the RS-232
flow control pins RTS or DTR. The Model
8179T terminal block input connects directly
to the RS-485 data bus.
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