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Modbus & Serial Output Transmitter
for Frequency, Rate or Period
Dual
channels. Rate and total in same transmitter.
DIN Rail mounted, digitally programmable.
Standard
Features
- Selectable Modbus or
Laurel ASCII protocol
- Modbus RTU or ASCII
modes, 2-wire connection, up to 247 digital addresses
- Two independently field-scalable
pulse input channels
- 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.
- Input signal scaled to six-digit readings:
- Digital span adjust from 0 to ±999,999
- Digital zero adjust from -999,999 to +999,999
- Selectable "count by" of 10 or 100 with
rounding
- Line frequency measurement to 60.0000 in a
few line cycles
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Square root extraction standard
- DIN rail mount package only 22.5 mm thick
- 5V, 10V or 24V dc sensor
excitation output, isolated
- Dual solid state relays for alarm or
control, isolated
- 0-10V, 4-20 mA or
0-20 mA transmitter output, isolated
- Universal AC power, 85-264 Vac
- Priced at only
$235
(basic pulse input transmitter)
Options:
- Extended Main Board
for rate and total simultaneously, custom curve
linearization, arithmetic functions A+B, A-B, AxB,
A/B, A/B-1 (draw)
- Low voltage power, 10-48 Vdc or 12-32 Vac
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Description
The Laureate Modbus &
serial output, frequency,
rate and period input transmitter 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. Applications 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
(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 curvilinear 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, which are available as options. 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 output 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
elongation of material between rollers).
 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. This results in
extremely accurate and stable 6-digit readings (±999,999 counts), which are
then scaled in software. The update rate of the transmitter output is a
programmed gate time + 30 ms + 0-2 signal periods. For a 60 Hz signal, the
update rate would be 20 per second. Such fast update rates are ideal for
alarm and control.
LTM Series serial output
transmitters send data via an isolated serial port, which is user
configurable for RS232 or RS485 and full or half duplex operation. 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.
It also allows use of
Laurel
Datalogging Software.
Standard features of Laureate
transmitters include:
- Serial data output, isolated.
User selectable RS232 or RS485, half or full duplex, Modbus or Laurel
ASCII protocol.
- Dual solid state relays for control
or alarm, isolated. 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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Analog transmitter output, 16-bit,
user scalable and isolated. User selectable 4-20 mA, 0-20 mA or 0-10V
levels.
- Universal AC power supply for
85-264 Vac.
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).
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Specifications
LTM-FR Modbus & Serial Output Transmitter for
Frequency, Rate or Period
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Pulse Input |
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Types
Ch A Frequency, Max
Ch B Frequency, Max
Signal Ground
Minimum Signal
Maximum Signal
Maximum Frequency
Contact Debounce
Time Base Accuracy
Span Tempco
Long-term Drift |
AC, pulses from NPN, PNP transistors,
contact closures,
magnetic pickups.
1 MHz
250 kHz
Common ground for channels A & B
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
±1 ppm/°C (typ)
±5 ppm/year |
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Serial Data Output
(standard) |
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Signal levels
Data Rates
Output Isolation
Serial Protocols
Devices on RS-485 Line
Modbus Addresses
Modbus Modes
Modbus Compliance |
RS232 or RS485 (half 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 (selectable)
32 max without a repeater.
247 max
RTU or ASCII, 2-wire.
Modbus over Serial Line Specification V1.0 (2002) |
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Dual Relay Output (standard) |
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Relay Type
Load Rating |
Two solid state relays, SPST, normally open,
Form A
130 mA at 140 Vac or 180 Vdc |
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Transducer Excitation Output (standard) |
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Output Levels
Output Isolation |
5V@100 mA, 10V@120 mA, 24V@50 mA (jumper
selectable)
50V from signal ground |
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Analog Output (standard) |
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Output Levels
Compliance, 4-20 mA
Compliance, 0-10V
Output Resolution
Output Accuracy
Output Isolation |
4-20 mA, 0-20 mA, 0-10 Vdc (jumper selectable)
10V ( 0-500 ohm load )
2 mA ( 5 kOhm load or higher)
16 bits (65,536 steps)
0.02% of output span
250V rms working, 2.3 kV rms per 1 minute test |
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Power Input |
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Standard Power
Low Power Option
Power Frequency
Power Isolation
Power Consumption |
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 |
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Mechanical |
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Dimensions
Mounting
Electrical Connections |
120 x 101 x 22.5 mm
35 mm rail per DIN EN 50022
Plug-in screw-clamp connectors |
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Environmental |
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Operating Temperature
Storage Temperature
Relative Humidity
Cooling Required |
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. |
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Application Examples of
Frequency / Rate Meters |
AC Line Frequency |
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Laureate frequency meters and transmitters accept line voltages up to 250 Vac and
output line frequency to 6-digit accuracy (50.0000 or 60.0000) in a few line cycles. Fast
low frequency response is achieved by timing the period and taking its inverse. |
RPM and Speed |
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Laureate frequency meters and transmitters can sense low-level signals from magnetic
pickups or the NPN or PNP transistor output of active sensors. These can be powered
directly by the meter or transmitter. Output in RPM or units of speed is
achieved by mathematical
scaling. |
Flow Rate and Simultaneous Total |
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Laureate frequency meters andtransmitters
are compatible with all flow
meters which
generate pulses at a frequency proportional to flow rate. The Extended version can display
scaled rate or total for the same input at the push of a button, and alarm from both the
rate and total. |
Combining Two Rates |
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Extended Laureate frequency meters and
transmitters offer A+B, A-B and A/B arithmetic
functions. A+B allows two input flows to be summed for total flow, while A-B allows
outflow to be subtracted from inflow for net flow. Flow ratios aid in the proper mixing of
ingredients. |
Custom
Curve Linearization |
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Extended Laureate frequency meters and
transmitters can linearize the output
turbine flow
meters, which tend to be nonlinear on the low end. Linearizing improves the
dynamic range and accuracy of turbine flow meters. |
System-level Capabilities |
Laureate dual-channel
rate meters and transmitters can independently scale, display and alarm two pulse input channels. All signal
or alarm data can further be transmitted via RS-232 or RS-485, including peak readings and
arithmetic combinations of the two rates. |
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Pinout
Laureate Modbus & Serial Output Transmitter
for Frequency, Rate or Period
Ordering
Guide
Laureate Modbus & Serial Output Transmitter for
Frequency, Rate or Period
Click
on the radio buttons to build a model number with pricing (shown below the
Ordering Guide).
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