Laurel Electronics LT: Ethernet & 4-20 mA Output Transmitter for Frequency, Rate or Period Input - Manual

LAUREL ELECTRONICS INC. , 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel 714-434-6131 • www.laurels.com 1
LAUREL
ELECTRONICS, INC.
Ethernet & 4-20 mA Output Transmitter
for Frequency, Rate or Period Input
Features
• Two independently field-scalable pulse input channels from 0.005 Hz to 1 MHz
• Inputs from NPN or PNP proximity switches, contact closures, digital logic,
magnetic pickups down to 12 mV, or AC inputs up to 250 Vac
• DIN rail mount housing only 22.5 mm wide, detachable screw-clamp connectors
• 4-20 mA or 0-10V transmitter output, jumper selectable, isolated
• Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span
• RS232 or RS485 serial data output, half or full duplex, isolated
• Modbus RTU, Modbus ASCII or Laurel ASCII protocol
• 5V, 10V or 24V dc transducer excitation output, isolated
• Dual solid state relays for alarm or control, isolated
• Universal AC power, 85-264 Vac, or low voltage power, 10-48 Vdc or 12-32 Vac
• Extended main board for simultaneous rate and total, custom curve linearization,
arithmetic functions A+B, A-B, AxB, A/B, A/B-1 (optional)
Description
The Laureate transmitter for frequency, rate or period accepts
two independently scalable input channels from a wide range of
pulse sources, such as NPN or PNP proximity switches, contact
closures, digital logic, magnetic pickups down to 12 mV, or AC
voltages to 250 Vac. Input frequencies can range from 0.005 Hz
to 1 MHz. The transmitter output can be selected as 4-20 mA,
0-20 mA or 0-10V, and is isolated to avoid ground loops. Appli-
cations include AC line frequency, RPM or speed from proximity
switch inputs, and flow from turbine flow meter inputs.
With a Standard Main Board, the transmitter output can be
scaled to track frequency in Hz, rate in engineering units (such as
gallons per minute), or period (inverse of frequency). Square root
extraction is standard.
With an Extended Main Board, the transmitter output can track
rate or totalized rate (such as gallons) whether the transducer
output is linear, requires square root extraction, or requires
custom curve linearization. The latter can be provided by a cur-
vilinear spline fit with up to 180 data points. The transmitter can
also count up to a preset total or down from a preset total to zero.
Such applications typically make use of optional dual solid state
relays. External reset of totals is via a special three-position
screw terminal connector. The two input channels A & B can also
be combined arithmetically to provide an analog transmitter out-
put that tracks A+B (e.g., sum of two flows), A-B (e.g., difference
of two flows), AxB (e.g., horsepower as product of force and
RPM), A/B (ratio of two flow), and A/B-1 (draw or relative elon-
gation of material between rollers).
Exceptional accuracy and stability in frequency measurement
are achieved by taking the inverse of period measured with a
calibrated quartz crystal time base. This results in extremely
accurate and stable 6-digit internal readings (±999,999 counts),
which are then processed in software. The analog output is
generated by an ultra-linear 16-bit (65,536 step) digital-to-analog
converter (DAC).
Standard features of Laureate transmitters include:
• 4-20 mA, 0-20 mA or 0-10V analog transmitter output,
isolated, jumper-selectable and user scalable. All selections
provide 16-bit (0.0015%) resolution of output span and 0.02%
output accuracy of a reading from -99,999 to +99,999 counts
that is also transmitted digitally. Output isolation from signal
and power grounds eliminates potential ground loop problems.
The supply can drive 20 mA into a 500 ohm (or lower) load for
10V compliance, or 10V into a 5K ohm (or higher) load for 2
mA compliance.
• Serial communications output, isolated. User selectable
RS232 or RS485, half or full duplex. Three protocols are user
selectable: Modbus RTU, Modbus ASCII, or Laurel ASCII.
Modbus operation is fully compliant with Modbus Over Serial
Line Specification V1.0 (2002). The Laurel ASCII protocol
allows up to 31 Laureate devices to be addressed on the
same RS485 data line. It is simpler than the Modbus protocol
and is recommended when all devices are Laureates.
• Dual solid state relays, isolated. Available for local alarm or
control. Rated 120 mA at 130 Vac or 170 Vdc.
• Transducer excitation output, isolated. User selectable
5V@100 mA, 10V@120 mA or 24V@50 mA.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or
12-32 Vac power is optional.
Easy Transmitter programming is via Laurel's Instrument
Setup Software, which runs on a PC under MS Windows. This
software can be downloaded from our website at no charge. The
required transmitter-to-PC interface cable is available from Laurel
(P/N CBL04).