Laurel Electronics LT 4-20 User Manual

LAUREL

tter for Ratio,

ELECTRONICS, INC.

4-20 mA & Serial Data Output Transmi

Product, Sum or Difference of 2 Rates or Totals

Features

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Two independently field-scalable pulse input channels A and B

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Arithmetic functions A+B, A-B, AxB, A/B, A/B-1 (draw) applicable to rate or total

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Frequencies from 0.005 Hz to 1 MHz

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Inputs from NPN or PNP proximity switches, contact closures, digital logic,
magnetic pickups down to 12 mV, or AC inputs up to 250 Vac

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4-20 mA or 0-10V transmitter output, jumper selectable, isolated

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Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span

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RS232 or RS485 serial data output, half or full duplex, isolated

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Modbus RTU, Modbus ASCII or Laurel ASCII protocol

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5V, 10V or 24V dc transducer excitation output, isolated

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Dual solid state relays for alarm or control, isolated

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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.

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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.

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Difference A-B can be used to subtract outflow from inflow for
net flow, or to subtract reject parts from total parts.

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Product AxB can be used to multiply two rates, for example
to compute horsepower by multiplying torque by RPM.

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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.

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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:

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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.

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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.

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Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12­32 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).

LAUREL

ELECTRONICS INC., 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel [phone] • www.laurels.com 1

Specifications

Pulse Input

Signal Types
Grounding
Channel A Frequency
Channel B Frequency
Minimum Signal
Maximum Signal
Noise Filter
Contact Debounce
Time Base Accuracy
Arithmetic Functions

Analog Output (standard)

Output Levels
Compliance, 4-20 mA
Compliance, 0-10V
Output Resolution
Output Accuracy
Output Update Rate
Output Isolation

Serial Communications (standard)

Signal Types
Data Rates
Output Isolation
Serial Protocols
Modbus Modes
Modbus Compliance
Digital Addressing

AC, pulses from NPN, PNP transistors, contact closures, magnetic pickups.
Common ground for channels A & B

0.005 Hz to 1 MHz

0.005 Hz to 250 kHz
Nine ranges from (-12 to +12 mV) to (+1.25 to +2.1V)
250 Vac
1 MHz, 30 kHz, 250 Hz (selectable)
0, 3, 50 ms (selectable)
Quartz crystal calibrated to ±2 ppm
A+B, A-B, AxB, A/B, A/B-1

4-20 mA and 0-10 Vdc (selectable)
10V ( 0-500 ohm load )
2 mA ( 5 kOhm load )
16 bits (65,536 steps)

0.02% of output span
Programmed gate time + 30 ms + 0-2 signal periods
250V rms working, 2.3 kV rms per 1 minute test

RS232 or RS485 (half or full duplex)
300, 600, 1200, 2400, 4800, 9600, 19200 baud
250V rms working, 2.3 kV rms per 1 min test
Modbus RTU, Modbus ASCII, Laurel ASCII
RTU or ASCII
Modbus over Serial Line Specification V1.0 (2002)
247 Modbus addresses.
Up to 32 devices on an RS485 line without a repeater.

Dual Relay Output (standard)

Relay Type
Load Rating

Sensor Excitation Output (standard)

Output Levels
Output Isolation

Power Input

Standard Power
Low Power Option
Power Frequency
Power Isolation
Power Consumption

Mechanical

Dimensions
Mounting
Electrical Connections

Environmental

Operating Temperature
Storage Temperature
Relative Humidity
Cooling Required

Two solid state relays, SPST, normally open, Form A
120 mA at 140 Vac or 180 Vdc

5V@100 mA, 10V@120 mA, 24V@50 mA (jumper selectable)
50V from signal ground

85-264 Vac or 90-300 Vdc (DC operation not UL approved)
10-48 Vdc or 12-32 Vac
DC or 47-63 Hz
250V rms working, 2.3 kV rms per 1 min test
2W typical, 3W with max excitation output

129 x 104 x 22.5 mm case
35 mm rail per DIN EN 50022
Plug-in screw-clamp connectors

0°C to 55°C

-40°C to 85°C
95% at 40°C, non-condensing
Mount transmitters with ventilation holes at top and bottom.
Leave 6 mm (1/4") between transmitters, or force air with a fan.

LAUREL

ELECTRONICS INC., 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel [phone] • www.laurels.com 2