Liquid Controls SP2800 - Manual (Page 35)

31
4-2 Analog Inputs (continued)
4-2.1 5A: 4-20 mA; 250
Ω
input impedance.
5B: 0-20 mA; 250
Ω
input impedance.
5C: 1-5 VDC; 15 K
Ω
input impedance.
5D: 0-5 VDC; 15 K
Ω
input impedance.
5E: 0-10 VDC; 15 K
Ω
input imped-
ance.
The above inputs take the analog signal and
scale it from 0 to 10000 pulses per second by
using a highly linear voltage to frequency con-
verter. These pulses go to the processor to
be scaled by the K Factors. To determine the
K Factor, see Section 7, Calculating the K
Factor.
4-2.2 6A: Square Law: 4-20 mA; 250
Ω
in-
put impedance.
The Square Law input is a special input that
compensates for non- linear input types. Spe-
cifically, inputs that require square root extrac-
tion to provide accurate count and rate deter-
minations. The input signal is converted to a
0 to 10000 pulse per second input to the pro-
cessor (See Table 4-2 below).
mA Input Freq. mA Input Freq.
4 0000 10 6123
5 2500 12 7071
6 3535 16 8660
7 4330 18 9354
8 5000 20 10000
Table 4-2
To calculate the freq. for a particular input use
the following formula.
mA - 4 x 10000 = Freq. to processor
16
For example: to calculate the frequency for 9
mA Input.
9 - 4 x 10000 = 5590 Freq. to processor.
16
4-2.3 Analog Inputs Exchange
If an analog sensor cannot be obtained that
matches the Batcher input, it is recommended
that the Batcher be returned to have the analog
input module exchanged and recalibrated.
Recalibration should only be attempted by
someone who has the training to open the unit
and work with grounded equipment necessary
to protect the static sensitive CMOS circuitry.
For instructions on how to return the unit for
exchange see Section 2-2.
4-2.4 Analog Inputs Calibration
(All units have been calibrated at the factory)
Warning: This unit contains static sensitive
components. Observe proper precautions!
a) Set the ratemeter at 6 SIG FIG; the
window at 01; and the K Factor at 1.00.
b) Remove the case and locate the analog
input card mounted behind the display
(see Section 6-3).
c) Locate the two 0.3 inch square pots R3
and R15. These numbers should be
silkscreened underneath them on the
board.
d) Input a very accurate low signal and
adjust R3 (left side from the front) so that
the display reads .0001 to 0000.
e) Input a very accurate high signal and
adjust R15 (right side from the front) so
that the display reads 9999 to 10000.
f) Repeat steps d and e until the unit is
reading as close as possible to 0000 on
the low side and 10000 on the high side.
This should only take a few tries.
g) Re-case the unit and setup the Menu as
desired.
If problems occur during calibration please con-
tact the factory for exchange or to arrange for
factory calibration.