Valleylab CUSA EXcel-8 - Introduction; Irrigation Pump; Machine Control Board

Machine Control Board
For any light bar to be illuminated, it must receive both the correct
segment and digit output from the display driver. Each LED light bar
(except for the numeric legends) has a unique map location; thus, each
LED light bar is independently controlled. The numeric legends are
controlled together, not independently.
Machine Control Board
Table 7-1.
Irrigation pump voltage steps
Introduction
The Machine Control board resides in the control panel assembly along
with the Display board. The Machine Control interfaces with the
ultrasonic section of the display and keypad. It also interfaces to the
solenoid valves, pumps, and the ultrasonic drive circuitry. This
description presents the Machine Control schematic. Refer to the
Schematics Supplement.
Irrigation Pump
A resistor divider and operational amplifier network establishes control
for the irrigation pump. The programmable logic device (PLD) sets the
levels. The signals are optically isolated and sent as inputs to a quad
analog switch. The analog switch selects gain resistors for an op amp,
which is amplifying a dc level. The op amps output drives a pump speed
controller (off board) which has a greater than 10k ohm input resistance.
The 5-bit output signal range for the irrigation pump is approximately
0 to 5V DC. The following table shows the irrigation steps:
irrigation step 5v_x=5.6v
display desired voltage setpoint theoret v
1 0.28 2 0.32
2 0.45 3 0.47
3 0.61 4 0.63
4 0.78 5 0.79
5 0.93 6 0.95
6 11 7 1.11
7 13 8 1.27
8 1.45 9 1.43
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