Intrinsic Safe Barrier Printed Circuit Board; Pulser Assembly; Photocoupler - Wayne Vista Series Service

3.4.1. Fault Codes, continued
Note: All fault codes will continue to be displayed until the problem which caused
them is remedied.
Error and Hydraulic codes are displayed every time the affected portion of the
dispenser is started by removing the nozzle from the nozzle boot and pressing
a start switch.
The format of the displayed fault codes is shown in Figure 3-2 and the defini-
tion of each code is shown in Table 3-1.
3.5.

INTRINSIC SAFE BARRIER PRINTED CIRCUIT BOARD

The Intrinsic Safe Barrier is located in the electronic head of the dispenser. Its function is
to ensure that the amount of electrical energy introduced into the hydraulics cabinet is
within acceptable limits. This barrier uses resistors and zener diodes to limit energy out
of the barrier. In the dispensing cycle, when the operating lever is lifted, the nozzle
switch moves to the closed position. This causes the nozzle signal on the computer base
to go from a +5 VDC potential to zero or ground potential, which cues the microproces-
sor to begin a new sale if the dispenser has been authorized and the push-to-start or cash/
credit select switch has been pressed.
The Intrinsic Safe Barrier Printed Circuit Board contains current limiting resistors and
voltage limiting redundant (2 in parallel) zener diodes which will limit voltage potential
to approximately 6.2 VDC. This energy limiting circuit eliminates the possibility of arcs
in the hydraulic area of the dispenser.
3.6. PULSER ASSEMBLY (see Figures 3-3 and 3-4)
The pulser assembly consists of two parts:
•

Photocoupler

• Pulser Disc
3.6.1. Photocoupler
The photocoupler consists of two infrared LED's and two phototransistors,
one for each LED. These four parts work together to provide two separate
pulse returns to the computer. These pulse return lines are labeled "Pulse A"
and "Pulse B". The computer must receive the pulses in an alternating se-
quence (i.e., pulse A, pulse B, A, B, A, B...). In this way the computer can
determine correct operation. If the computer sees too many A or B pulses in a
row it will assume that the photocoupler is defective, shut down the sale and
generate a fault code (see Table 3-1). If the computer sees that the meter is
turning in the wrong direction, it will shut down the sale and generate a fault
code (see Table 3-1).
November 1992 Part No. 917543 Rev. A
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