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LTM-FR 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.
-
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, 95-240 Vac ±10%
- 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 12-30 Vac.
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Description
The Laureate
LTM-FR 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 Model
LTM-FR 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.
-
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 95-240 Vac ±10%.
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 I/O Transmitter
for Frequency, Rate or Period
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Pulse Input |
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) |
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) |
Relay Type
Load rating |
Two solid state relays, SPST, normally open,
Form A
120 mA at 130 Vac or 170 Vdc, 28 ohms in series |
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Transducer Excitation Output (standard) |
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) |
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 bit DAC
±0.02% of output span plus conversion accuracy
250V rms working, 2.3 kV rms per 1 minute test |
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Power Input |
Standard power
Low power option
Frequency
Power Isolation |
95-240 Vac ±10% or 90-300 Vdc (DC operation not UL approved)
12-30 Vac or 10-48 Vdc
DC or 47-63 Hz
250V rms working, 2.3 kV rms per 1 min test |
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Mechanical |
Case Dimensions
Case Mounting
Electrical Connections |
120 x 101 x 22.5 mm
35 mm rail per DIN EN 50022
Detachable screw clamp plug connectors |
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Environmental |
Operating Temperature
Storage Temperature
Relative Humidity |
0°C to
70°C
-40°C to 85°C
95% at 40°C, non-condensing |
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Application Examples |
AC Line Frequency |
 |
The Laureate will accept line voltages up to 250 Vac and
display 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 |
 |
The Laureate can sense the low-level signals from magnetic
pickups or the NPN or PNP transistor output of active sensors. These can be powered
directly by the meter. Display in RPM or units of speed is achieved by mathematically
scaling the meter. |
Flow Rate and Simultaneous Total |
 |
The Laureate is 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. The Extended version can also linearize flow transducers so as to extend
their dynamic range. |
Combining Two Rates |
 |
The Extended Laureate offers 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 |
 |
The Extended Laureate 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 |
The Laureate dual channel
rate meter 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. The displayed rates can also be transmitted as
isolated isolated 4-20 mA or 0-10V analog output. |
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Pinout
LTM-FR Modbus & Serial I/O Transmitter
for Frequency, Rate or Period
Ordering
Guide
LTM-FR Modbus & Serial I/O Transmitter
for Frequency, Rate or Period
Click
on the radio buttons to build a model number with pricing.
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