990 CLD Autoline™ Leak Detector
DR
AFT 2/2/04
3-11
Remote Exponent Control Operation
Three isolated pairs of inputs are provided for remotely controlling the range that appears
on the bar graph. The EXPONENT R/L pair, pins 15 (+) and 16 (-) of item 10 in Figure 1-5 on
page 1-10, determine remote or local operation of display ranging.
❑
Apply a voltage of 5 V to this pair and the console reads ranging information from the
rear panel inputs as opposed to reading the
Range
UP
, and
DOWN
switches on the
front panel.
The LSB and MSB pairs, positions 13 (+) and 14 (-) of item 10 (Figure 1-5 on page 1-10) and
pins 17 (+} and 18 (-) of item 10, respectively, determine which of the four ranges are
selected. MSB and LSB, taken together, represent a two-digit binary number:
❑
Voltage applied represents a
1
.
❑
No voltage applied represents a
0
.
This number, added to the number indicated on the RANGE SELECT switch, is the digit that
appears as the exponent on the bar graph. Table 3-3 is a truth table for this function.
For example, if the RANGE SELECT switch is set to 3 and a voltage is applied to R/L and
MSB and no voltage is applied to LSB. The console is in remote mode as R/L has voltage.
The binary number from MSB and LSB is 2, because MSB is a
1
and LSB is a
0
, together they
make 10 binary, which is 2 in decimal form. 5 appears as the exponent as the RANGE
SELECT switch is set to
3
and the binary number is 2 (3 + 2 = 5).
Table 3-2
Exponent Selection, Local Mode
Range Select
Switch
Setting
0 1 2 3 4 5 6 7 8 9
Smallest
exponent
displayed*
0 1 2 3 4 5 6 7 8 9
Next
largest*
1 2 3 4 5 6 7 8 9 B
Next
largest*
2 3 4 5 6 7 8 9 B B
Largest
exponent
displayed*
3 4 5 6 7 8 9 B B B
B = Blank exponent
* = Exponents are changed by pressing RANGE DOWN/UP pushbuttons
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