3
LEVELtrol-II Installation & Operating Instructions
Analog Output
The analog output is menu assignable to
correspond to the Uncompensated Volume Level,
Corrected Volume Level, Mass, Temperature,
Density.
Type: Isolated Current Sourcing
Isolated I/P/C: 500 V
Available Ranges: 4-20 mA
Resolution: 12 bit
Accuracy: 0.05% FS at 20 Degrees C
Update Level: 1 update/sec minimum
Temperature Drift: Less than 200 ppm/C
Maximum Load: 1000 ohms (at nominal line
voltage)
Compliance Effect: Less than .05% Span
60 Hz rejection: 40 dB minimum
EMI: No effect at 3 V/M
Calibration: Operator assisted Learn Mode
Averaging: User entry of DSP Averaging constant
to cause an smooth control action.
Isolated Pulse output
The isolated pulse output produces pulses based
on the changing Uncompensated Volume Total,
Compensated Volume Total or Mass Total.
Usage: Quantity entering or leaving tank
Isolation I/O/P: 500 V
Pulse Output Form: Open Collector
Maximum On Current: 25 mA
Maximum Off Voltage: 30 VDC
Saturation Voltage: 1.0 VDC
Maximum Off Current: 0.1 mA
Pulse Duration: 10 msec or 100 msec
Pulse output buffer: 8 bit
Fault Protection
Reverse polarity: Shunt Diode
Transient Protection: 500 VDC
(Capacitive Clamp)
RS-232 Communication
Uses: Printing, Setup, Modem, Datalogging
Baud Rates: 300, 600, 1200, 2400, 4800, 9600,
19200
Parity: None, Odd, Even
Device ID: 0 to 99
Protocol: Proprietary, Contact factory for more
information
Chassis Connector Style: DB 9 Female connector
RS-485 Communication (optional)
Uses: Network Communications
Baud Rates: 300, 600, 1200, 2400, 4800, 9600,
19200
Parity: None, Odd, Even
Device ID: 0 to 247
Protocol: ModBus RTU
Chassis Connector Style:
DB 9 Female connector,
Terminal Block Optional
Operating Mode
The LEVELtrol-II can be thought of as making a
series of measurements of level, temperature/
density sensors and then performing calculations
to arrive at a result(s) which are then updated
periodically on the display. The analog output, the
pulse output, and the alarm relays are also updated.
The cycle then repeats itself.
Step 1: Update the measurements of input signals
Raw Input Measurements are made at each input
using equations based on input signal type selected.
The system notes the “out of range” input signal as
an alarm condition.
Step 2: Compute the Flowing Fluid Parameters
The temperature and density equations are
computed as needed based on the instrument
equations and input usage selected by the user.
Step 3 : Compute the Tank Level
The value is computed based on the level sensor
input type selected and by installation details on the
tank and fluid properties.
Step 4: Compute the Uncorrected Tank Volume
Compute the uncorrected tank volume from
the tank level measurement and known geometry
of the tank.
Step 5: Compute the Corrected Tank Volume at
Reference Conditions or Mass in tank.
Step 6: Check Alarms
The alarm functions have been assigned to one
of the above during the setup of the instrument. A
comparison is now made by comparing the current
value against the specified hi and low limits.
Step 7: Compute the Analog Output
This designated process value is now used to
compute the analog output.
Step 8: Total Preset Comparisons
The total associated with a preset function is then
compared against the corresponding preset value
and any required control actions taken.
Step 9: Pulse Output Service-
The pulse output is next updated by scaling the total
increment which has just been determined by the
pulse output scaler and summing it to any residual
pulse output amount.
Step 10: Update Display and Printer Output-
The instrument finally runs a task to update the
various table entries associated with the front panel
display and serial outputs.
