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Pin 6/E - Data Set Ready
For nailed-up connections Data Set Ready will be ON while power is available, including during
loopback testing.
For circuit switched connections, it turns ON in response to an incoming call or when making an
outgoing call. This lead also turns ON upon initiation of local loopback testing. This lead turns OFF
when a data call is terminated, and upon termination of local loopback testing.
Pin 8/F - Received Line Signal Detect
For circuit switched full-duplex operation, this circuit indicates the presence of a data connection.
The OFF to ON transition of this signal occurs within 15 to 150 msec after a data call has been
connected. The ON to OFF transition occurs within 15 msec after the data call is terminated. This
circuit is always ON in the nailed-up 64 kbps mode.
For half-duplex emulation operation, this circuit turns ON as it would with full-duplex operation
provided that Request to Send is at the remote end. This circuit is turned OFF when Request to Send
turns OFF at the remote end, or when a circuit switched call is terminated.
Pins 3/R and 3/T - Received Data
Signals on this circuit are generated by the 7500 in response to data received from the remote data
equipment. The 7500 presents each signal element on the OFF to ON transition of the Receiver Signal
Element Timing circuit.
When the 7500 has been placed in a loopback mode by the remote terminal adapter, received
data is clamped to one.
Pins 17/V and 17/X - Receiver Signal Element Timing
This circuit is used to provide the DTE with timing information for data reception. Each signal
element on the Receive Data circuits occurs at the OFF to ON transition of these timing circuits. The
ON to OFF transition of this circuit indicates when the DTE should read the data on the Receive Data
circuits.
Pins 15/Y and 15/AA - Transmitter Signal Element Timing
This circuit is used to provide the DTE with timing information for data generation. The OFF to
ON transition of this circuit indicates when the DTE should present the data on the Transmit Data
circuits. The 7500 will sample the Transmit Data circuits on the ON to OFF transitions of these timing
circuits.
Pins 2/P and 2/S - Transmitted Data
The 7500 recognizes data generated by the DTE when Request to Send lead is ON. The 7500 will
sample this circuit on the ON to OFF transition of the Transmitter Signal Element Timing circuit.
Pin 20/H - Data Terminal Ready
An ON signal from the attached DTE indicates to the 7500 that the DTE is ready to be connected to
the network. An OFF condition for more than 50 msec during data call setup, while in the data transfer
mode, or during a test sequence, causes the 7500 to clear any circuit switched call or terminate the test.
CHAPTER 9: TECHNICAL INFORMATION
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