GE L90 Instruction Manual page 91

3 HARDWARE
figuration, the timing for both data modules and both UR–RS422 channels are derived from a single clock source. As a
result, data sampling for both of the UR–RS422 channels is synchronized via the send timing leads on data module 1 as
shown below. If the terminal timing feature is not available or this type of connection is not desired, the G.703 interface is a
viable option that does not impose timing restrictions.
Figure 3–36: TIMING CONFIGURATION FOR RS422 TWO-CHANNEL, 3-TERMINAL APPLICATION
Data module 1 provides timing to the L90 RS422 interface via the ST(A) and ST(B) outputs. Data module 1 also provides
timing to data module 2 TT(A) and TT(B) inputs via the ST(A) and AT(B) outputs. The data module pin numbers have been
omitted in the figure above since they vary by manufacturer.
c) TRANSMIT TIMING
The RS422 interface accepts one clock input for transmit timing. It is important that the rising edge of the 64 kHz transmit
timing clock of the multiplexer interface is sampling the data in the center of the transmit data window. Therefore, it is impor-
tant to confirm clock and data transitions to ensure proper system operation. For example, the following figure shows the
positive edge of the Tx clock in the center of the Tx data bit.
GE Multilin
W 2a
Tx1(+)
Tx1(-) W 3b
RS422
Rx1(+) W 4b
CHANNEL 1
Rx1(-) W 3a
W 6a
Shld.
+ W 7a
CLOCK
–
W 8b
W 4a
Tx2(+)
Tx2(-) W 5b
RS422
W 6b
Rx2(+)
CHANNEL 2
Rx2(-) W 5a
W 7b
Shld.
com W 2b
SURGE W 8a
Tx Clock
Tx Data
Figure 3–37: CLOCK AND DATA TRANSITIONS
L90 Line Current Differential System
3.3 PILOT CHANNEL COMMUNICATIONS
Data module 1
Signal name
SD(A) - Send data
SD(B) - Send data
RD(A) - Received data
RD(B) - Received data
RS(A) - Request to send (RTS)
RS(B) - Request to send (RTS)
RT(A) - Receive timing
RT(B) - Receive timing
CS(A) - Clear To send
CS(B) - Clear To send
Local loopback
Remote loopback
Signal ground
ST(A) - Send timing
ST(B) - Send timing
Data module 2
Signal name
TT(A) - Terminal timing
TT(B) - Terminal timing
SD(A) - Send data
SD(B) - Send data
RD(A) - Received data
RD(B) - Received data
RS(A) - Request to send (RTS)
RS(B) - Request to send (RTS)
CS(A) - Clear To send
CS(B) - Clear To send
Local loopback
Remote loopback
Signal ground
ST(A) - Send timing
ST(B) - Send timing
831022A3.CDR
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