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2.4.1.3 Control signals circuit
LINESYNC, POWERUP and POWERDN are the external interruption signals used to generate internal
CPU’s control signals.
These signals are generated at the 2070-4A module power supply, routed to the Serial Motherboard and
received through the A5 connector.
Once received these signals are routed to the Engine Board through the P2 connector. Also, these
signals are inverted, isolated (POWERUP is ORed with CPULRESET at this stage to generate the
RESET signal), converted to differential line signals and then routed to C13S connector.
2.4.1.4 Receptacles for engine board installation
P1 and P2 are the two 50-position receptacle connectors that provide an interface between the Engine
board and Host board, they carry the RS-485 differential signals for the serial communication ports SP-1,
SP-2, SP-3, SP-4, SP-5, SP-6, and SP-8; for the SPI bus, also the CPU_ACTIVE LED, Ethernet,
DATAKEY and USB lines, +5VSTANDBY and interruption signals LINESYNC, POWERUP and
POWERDOWN.
2.4.1.5 RS-485 line driver/receivers circuitry
The RS-485 line driver/receiver circuitry is the interface for the serial communication ports between the
serial motherboard and the Engine Board. This stage converts the RS-485 differential signals provided by
the serial motherboard at A5 connector to a single ended signal to be used by the Engine Board. This
circuitry also receives the single ended signals from the Engine Board and converts them to RS-485
differential signals to be sent to the serial motherboard. Some enabling/disabling control for the receivers
and drivers is added at this stage.
Receivers:
The differential signals coming from the serial motherboard through A5 enter to the line receivers to be
converted into single ended signals and then routed to the Engine Board through the P1/P2 connectors.
Five quadruple differential line receivers SN65LBC173A are used to receive the serial communication
differential signals of SP-1, SP-2, SP-3, SP-4, SP-5 and SP-6 ports. The two enable inputs of the line
receiver are accordingly tied to +5VDC and GND, permanently enabling all receivers, then the reception
of serial communications is always enabled.
Reception signals:
SP-1: RxD+, RxD-, CTS+, CTS-, TxCLKI+, TxCLKI-, RxCLK+, RxCLK-, DCD+, DCD-.
SP-2: RxD+, RxD-, CTS+, CTS-, TxCLKI+, TxCLKI-, RxCLK+, RxCLK-, DCD+, DCD-.
SP-3: RxD+, RxD-, CTS+, CTS-, TxCLKI+, TxCLKI-, RxCLK+, RxCLK-, DCD+, DCD-.
SP-4: RxD+, RxD-.
SP-5: RxD+, RxD-, RxCLK+, RxCLK-.
SP-6: RxD+, RxD-.
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