16
LD485S-MP
3.1.2 T
RANSMIT
D
ATA
C
LOCK
Data timing is synchronized among all connected devices in one of three ways:
• Internal Clock (factory setting)
• Recovered Clock
• External Clock
Internal Clock —
Line Driver generates transmit data clock and presents
clock to attached DTE via Pin 15. The DTE then presents
synchronized data to the LD485S on Pin 2.
Recovered Clock —
Transmit data clock is presented to the DTE on Pin 15,
synchronized with timing of data received from the remote
device. The DTE then presents synchronized data to the
LD485S on Pin 2.
External Clock —
Clocking is determined by local DTE. The clock is
presented to the Line Driver on Pin 24, and returned on
Pin 15. The DTE then presents synchronized data to the
LD485S on Pin 2.
Table 3-2. Transmit Clock Options (Switch 6)
Switch 6, Position
Pin 15 Clock Source
4
3
2
1
Internal*
ON
OFF
ON
OFF
Recovered
ON
OFF
OFF
ON
External
ON
ON
OFF
OFF
Pin 15 Disabled
OFF
—
—
—
*factory setting
To achieve a master clock, one of the Line Drivers should be set to internal or
external clocking and the other Line Driver(s) set to recovered clock.
