Transmitter Board
The transmitter board assembly consists of the signal conditioning circuit,
microprocessor, LC display and 4-20 mA output circuit. The transmitter board
assembly is connected to the connection board via ribbon cable and secured
onto the stand-off via two thumb screws. To remove the transmitter board
simply move the thumb screws counter-clockwise and slowly pull the transmitter
board away. Unplug the ribbon cable to completely remove the transmitter
board from sensor unit.
Note: Do not use force to tighten the thumb screws when installing the
transmitter board back on the connection / termination board.
Connection Board
The termination or connection board consists of relays and DC-DC power
converters for the transmitter board and the sensor. The power converters are
protected against reverse polarity.
A 3 pin terminal is provided for user interface to the monitoring device for power
input and 4-20ma output. Three (3) Pin terminal blocks are also used for alarm
connections. Each pin on alarm terminal block is labeled as C (common), NC
(normally closed) and NO (normally open). See Figure 3.
The 4 pin terminal at the bottom of the board is labeled
SENSOR.
Wires from the
sensor head assembly are connected to this terminal.
Each terminal contact is labeled as R(ed), G(reen), W(hite), B(lack). the toxic
sensors are 4 wires while Hydrocarbons LEL (Catalytic bead) and all infrared
sensors are 3 wires.
See figure 2 for drawing of Transmitter board and connection board assembly.
