2070LX Controller – User Manual 39
Version 1.0
Connectors
150-Positions header
This is a 150-pins high density 2mm male header connector used to interconnect the main board (which
support all of the input/output, power, isolation and control circuitry) and the connector board (which
support all of the necessary connectors for the field interface) that has the mating female receptacle.
A3 Connector
It is a 96-pin right angle DIN connector used to interface the Field I/O module to the serial mother board.
It carries the signals and power lines for:
The serial ports SP-3 and SP-5.
The control signals: LINESYNC, POWERUP, POWERDOWN and CPURESET.
The +5VDC voltage that is used to feed the circuitry at the non-isolated side, the line driver and
line receiver, the inverter gates, the opto-isolators and the toggle switch.
The +12VDC ISO voltage that is then converted to +5VDC ISO in order to feed all Control and I/O
circuitry.
Isolation Stage
The Field I/O module is the module for interfacing the Controller with the real world so that it is isolated
from the system in order to avoid all kind of problems related to the field such as ground loops, induced
noise, etc.
The module optically isolates the transmission and reception lines of serial ports SP-3 and SP-5;
therefore, all communication lines between the CPU and Field I/O module are isolated.
The serial ports come from the CPU through the Serial Motherboard and are present at A3 connector; the
RS485 communication signals entering to the Field I/O module are converted to single ended lines and
are then isolated; also, the communication lines going to the CPU are isolated and then converted to
RS485 signals. The isolation is achieved by using optically coupled logic gates that combine a light
emitting diode and a photo detector. The detector’s output is an open collector transistor. This stage
provides circuit isolation and high speed logic interfacing at induced noise environments.
The Control and I/O circuitry is fed with +5VDC ISO, that is obtained from the ISO +12VDC coming from
the 2070-4A Power Supply and present at A3 connector.
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