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Communication with the Card Reader System (SPM) - The
dispenser provides power for the card reader and printer. The
power and data is routed from the Power Distribution Board
(TS4), through the CPU Board and to the SPM terminal strip TS4
(see figure 4.9). TS4 is the 3 terminal connector that connects the
dispenser card reader channel with the Bennett IC box in the
store using RS-485 twisted pair field wiring communication.
The communication for the SPM between the CPU Board and the
Power Distribution Board is through the same ribbon cable as the
dispenser fuel (Current Loop) communication (see figure 4.10). It
exits the CPU Board on connector J8 and enters the Power
Distribution Board on J3. It exits the board on Terminal Strip TS4.
Communication with the Handle Switch - When the customer
removes the nozzle from the nozzle boot, a small electronic
circuit is activated sending a signal through the Intrinsically Safe
Barrier to the CPU Board. This signal is dependent on the jumper
setting on the circuit board. The CPU Board interprets this
voltage as the identifier for the handle. That is, it sees it as
Handle "A". If the jumper setting is wrong then the handle switch
will not call in correctly.
Communication with the Meter - The CPU Board reads sale
data provided by the Meter's Remote Core via the Communication
Hub Board (see figure 4.11).
System Software -
Two system Programmable Read Only
Memory (EPROM's) chips run the dispenser's operating program.
These chips are located in slots U25 and U30 (see figure 4.12).
The chips have markings on them that describe the software
revision level (which can also be seen in diagnostics), the
Bennett part numbers and the date code of the chips. These are
replaceable chips, but should not be replaced by untrained
personnel.
System Memory (RAM) - The CPU Board contains 128K of non
volatile RAM (see figure 4.12). The RAM is the area of the
microprocessor that does all of the calculations. It is sometimes
referred to as the "scratch pad" or "chalk board" because it keeps
getting written to and erased. For information on clearing the
RAM see section later in this chapter.
CPU Board
Figure 4.9 - Card reader communication
Figure 4.10 - Ribbon cable handles SPM and
console communication information.
Figure 4.11 - Communication Hub Board
RAM
Figure 4.12 - System software - 2 EPROM's
located in slots U25 and U30.
28
125870 Rev A 8-12-14
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