2070LX Controller – User Manual 11
Version 1.0
2.4 THEORY OF OPERATION
The module contains all the circuitry for the CPU function: main processor, FLASH memory, SRAM, RTC,
a bidirectional buffer bank for the data, address lines and control lines coming from the processor, the
back-up capacitor, RESET circuit, isolation circuit for control signals coming from the power supply,
isolation circuit for SP8, C13S connector, Ethernet circuit, DATAKEY circuit, SD card circuit, USB circuit,
driver field circuit (RS-485 transceivers), LINESYNC circuit, A2 and A3 connector sensor and A5
connector.
The module is comprised of three main parts: A Host Board, an Engine Board and a Faceplate.
The faceplate is a 2X wide aluminum front plate with the necessary cutouts for the front connections; it
also has thumbscrews to be attached to the chassis.
2.4.1 Host board
This board provides the mechanical and electrical interface to the Engine Board. All circuitry related to the
power, communications, control, status, and signal conditioning to be provided to the Engine board is
done here.
The board includes: DIN-96 connector, C13S Connector circuitry, control signals circuitry (Power Down,
Power Up, Linesync and CPU Reset), receptacles for engine board installation, voltage regulators, RS-
485 line driver/receiver circuitry, backup circuitry, Ethernet switch, USB, Datakey circuitry, SD card
receptacle, ACTIVE LED circuitry, A2-A3 installation detection circuitry, ESD protection, etc.
2.4.1.1 The DIN-96 Connector
The 96-pin DIN connector is the physical interface between the CPU and the serial motherboard A5 slot.
It carries the RS-485 differential signals for the serial communication ports SP-1, SP-2, SP-3, SP-4, SP-5
and SP-6; the Ethernet port lines, A2 and A3 install lines, FPALED line, CPURESET line, and the
interruption signals LINESYNC, POWERUP and POWERDOWN.
2.4.1.2 C13S Connector circuitry
C13S Connector is a 25-positions D-sub connector that is used to support the serial communication port
SP-8 and the control lines (Linesync, Reset, Power Down).
It consists of RS-485 drivers and receivers, opto-isolators and inverter gates.
SP-8 single ended transmission signals TxCLKO, RTS and TxD coming from the Engine Board
(Connector P2) are inverted, isolated, converted to differential line signals at the differential line driver and
then routed to the C13S connector.
SP-8 differential line signals RxCLK+, RxCLK-, RxD+, RxD-, CTS+, CTS-, DCD+, DCD-, received at the
C13S connector are converted to single ended signals at the differential line receiver, isolated and then
routed to the Engine Board through the connector P2.
The +5VDC isolated power supply is achieved by using the incoming +12VDC ISO from 2070 power
supply, a +5VDC voltage regulator and two capacitors.
This isolated supply is used to power the isolation circuitry and RS-485 circuitry for SP-8 communication
signals and external interrupts, also as an isolated supply at C13S connector.
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