Laurel Electronics LT: 4-20 mA & Serial Data Output Transmitter for Ratio - Manual

LAUREL ELECTRONICS INC. , 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel 714-434-6131 • www.laurels.com 1
LAUREL
ELECTRONICS, INC.
4-20 mA & Serial Data Output Transmitter for Ratio,
Product, Sum or Difference of 2 Rates or Totals
Features
• Two independently field-scalable pulse input channels A and B
• Arithmetic functions A+B, A-B, AxB, A/B, A/B-1 (draw) applicable to rate or total
• Frequencies 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
• 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
Description
The Laureate dual pulse input transmitter accepts two inde-
pendently scalable input channels A & B 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.
Arithmetic functions A+B, A-B, AxB, A/B or A/B-1 are made
available by the Extended counter main board and can track the
sum, difference, product, ratio, or draw of both input channels.
These functions can be applied to scaled rates, scaled totals,
square root of rates, totals after square root extraction, custom
curve linearized rates, or totals after custom curve linearization.
• Sum A+B can be used to add two flows for total flow, or to
add the number of parts carried by two conveyor belts.
• Difference A-B can be used to subtract outflow from inflow for
net flow, or to subtract reject parts from total parts.
• Product AxB can be used to multiply two rates, for example
to compute horsepower by multiplying torque by RPM.
• Ratio A/B can be used to compare flow rates in two channels,
the RPM of rollers or gears, or the speed of moving machinery
such as conveyor belts. Ratio can also be applied to scaled
totals to compare two batches to be mixed. In this application,
one transmitter is used to monitor the ratio of flow rates, and a
second transmitter to monitor the resulting batch totals.
• Draw A/B-1 is obtained by subtracting 1 from ratio. Draw is
used to measure the elongation of material as it passes
between rollers, or to monitor variation in the speed of rollers
for tensioning.
Exceptional Accuracy and Stability. Laureate pulse input
frequency and rate transmitters determine frequency by taking
the inverse of period as measured with a calibrated quartz crystal
time base. Extremely accurate 6-digit internal readings (±999,999
counts) are processed in software.
The update rate of the transmitter output is a programmed gate
time + 30 ms + 0-2 signal periods. For pulse rates of 60 Hz and
above, the update rate would be 20 per second. Such fast update
rates are ideal for alarm and control.
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 500Ω (or lower) load for
10V compliance, or 10V into a 5 kΩ (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 this website at no charge. The
required transmitter-to-PC interface cable is available from Laurel
(P/N CBL04).