CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 66)

Chapter 4 Data Interfaces 2240 Fiber Optic Modem User Manual
TTL/BNC Interface Model -BN
66
Figure 4-3 Example of Link Between Bipolar and Clocked Interface
4.8 TTL/BNC Interface Model -BN
This model uses BNC (bayonet) connectors for the physical interface. The electrical signal
characteristics are unbalanced TTL levels, with only the clock and data circuits supported. Four
BNC connectors are supplied for connection to a DTE device.
High speeds and long distances (clock and data only) can be achieved using this interface.
This interface version has a switchable dual purpose port for the Send Timing (SCT) and
Terminal Timing (SCTE) clock signals. A two-position slide switch (S1) on the interface card
controls the port direction.
When the switch is set towards the BNC connectors, the port is configured as an input (for the
SCTE clock). Sliding the switch away from the BNC connectors configures the port as an output
(for the SCT clock). (See Figure 4-4 for connectors and refer to Table 4-16 for signals supported.)
NOTE: When setting up the clock select, the proper main circuit board clock mode
must be set correctly, i.e., external for the SCTE clock input, slave or
internal for the SCT clock output.
T1
2240
(mode 7)
2240
(mode 5
Slave)
V.35
Rx
Tx
Data
Clk Tx
Data
Clk Rx
4B1
436