Each of the 16 data streams on the SCbus is interfaced to the SCX160 SCxbus Adapter via a corresponding data transceiver, as shown in Figure 4. Each SCbus interface transceiver comprises individually controlled tri-state drivers and permanently enabled receivers. These drivers are controlled by the on-board 80C186 Control Processor. The firmware only enables those drivers that will transmit onto the SCbus or the SCxbus.
Each of the 16 data streams on the SCxbus is interfaced to the SCX160 SCxbus Adapter via a corresponding, individually controlled, RS-485 data transceiver (tri-state drivers and permanently enabled receivers) (see Figure 4).
At Dialogic service startup, each data stream (DS0 through DS15) is configured to transmit data from the SCbus to the SCxbus, or to transmit data from the SCxbus to the SCbus.
To illustrate, assume that SCbus data stream 0 outbound (DS0 OUT), comprising time slots 0 to 63, enters the SCX160 SCxbus Adapter via SCbus data transceiver receiver 1A (see Figure 4). DS0 OUT is then applied to the SCxbus FIFO elastic buffer and then via the SCxbus data transceiver driver 1B to the SCxbus. Since DS0 is transmitting into the SCbus interface of the SCX160 SCxbus Adapter, the SCbus data transceiver driver 1A is disabled by the Control Processor to guard against inadvertently corrupting this data stream. At the SCxbus data transceiver interface, both driver 1B and receiver 1B are enabled. Driver 1B transmits the data stream onto the SCxbus and to receiver 1B. Receiver 1B output is monitored by the Test Access Logic.
To illustrate transmitting data from the SCxbus to the SCbus, assume that SCxbus data stream 1 inbound (DS1 IN), comprising time slots 64 to 127, enters the SCX160 SCxbus Adapter via SCxbus data transceiver receiver 2B (see Figure 4). DS1 IN is then applied to the SCbus FIFO elastic buffer and then via the SCbus data transceiver driver 2A to the SCbus. Since DS1 is transmitting into the SCxbus interface of the SCX160 SCxbus Adapter, the SCxbus data transceiver driver 2B is disabled by the Control Processor to guard against inadvertently corrupting this data stream. At the SCbus data transceiver interface, both driver 2A and receiver 2A are enabled. Driver 2A transmits the data stream onto the SCbus and to receiver 2A. Receiver 2A output is monitored by the Test Access Logic.
Figure 4. SCbus/SCxbus Data Stream Connections & Test Access
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