4-20 mA Current Output Transmitter for Ratio,
Product, Sum or Difference of 2 Rates or Totals
Applicable to Rate or Total for two pulse channels A & B.
DIN Rail mounted, digitally programmable.

Standard Features

Isolated 4-20 mA or 0-10V transmitter outputs, selectable

Two independently field-scalable pulse input Channels A & B

Internal conversion of Channel A & B inputs to six-digit readings:
- Digital span adjust from 0 to ±999,999
- Digital zero adjust from -999,999 to +999,999

Applicable arithmetic functions: A+B, A-B, AxB, A/B, A/B-1 (draw)

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.

Output resolution: 0.0015% of span (16 bits)

Output accuracy: ±0.05% of span

High update rate

Square root extraction standard

DIN rail mount package only 22.5 mm thick

Plug-in screw-clamp connectors

Easy setup with PC-based Instrument Setup Software

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

Dual solid state relays for alarm or control, isolated

RS232 or RS485 serial communications, isolated

Universal AC power, 85-264 Vac

Priced at only $275 (basic arithmetic transmitter)
Options:

Low voltage power, 10-48 Vdc or 12-32 Vac

Description

The Laureate 4-20 mA output, pulse input transmitter accepts two independently 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 to track the sum, difference, product, ratio, or draw of both input channels are available with the Extended main board. These arithmetic operations 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 can be used to add two flows for total flow, or to add the number of parts carried by two conveyor belts.
Difference can be used to subtract outflow from inflow for net flow, or to subtract reject parts from total parts.
Product can be used to multiply two rates, for example to compute horsepower by multiplying torque by RPM.
Ratio 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 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.

Signal conditioner board used with 4-20 mA current transmitter for frequency, rate or period 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 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) for 0.02% output accuracy.

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 Model LTA-R include:

Analog transmitter output, 16-bit, user scalable and isolated. User selectable 4-20 mA, 0-20 mA or 0-10V levels.
Serial communications, 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.
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).

Specifications
Laureate 4-20 mA Transmitter for Ratio, Product, Sum or Difference of 2 Inputs

Pulse Input

Types

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

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

Analog Output

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

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

Sensor Excitation Output (standard)

Output Levels
Output Isolation

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

Dual Relay Output (standard)

Relay Type
Load Rating

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

Serial Communications (standard)

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

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 w/o a repeater.

Power Input

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

Mechanical

Dimensions
Mounting
Electrical Connections

120 x 101 x 22.5 mm
35 mm rail per DIN EN 50022
Plug-in screw-clamp connectors

Environmental

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.

Application Examples of Ratio Meters
Controlling the Mixing Ratio of Two Fluids
	Transmitting and alarming the input flow rate ratio of two fluids (gas or liquid) allows these to be mixed in a predetermined ratio in continuous processes. The sensing element is normally a turbine flow meter, which outputs pulses at a frequency proportional to flow rate. The A/B ratio can also be transmitted for totalized rate (or delivered volume).
Comparing Fluid Inflow & Outflow
	The ratio of the inflow and outflow rates of a tank is a measure of the relative filling or emptying rate. The same transmitter can also be programmed to transmit the net inflow or outflow rate in flow units, or to transmit totalized inflow our outflow in volume units. Any of these parameters can be alarmed using the dual relay board and be transmitted via 4-20 mA.
Controlling Coating Thickness on a Film
	In this application, Channel A measures the rate at which a coating material is applied, as measured by a flow meter, while Channel B measures the speed of the film based on pulses from a proximity switch. Transmitting and alarming the A/B ratio assures that an even thickness of coating material is applied as the speed of the film is varies.
Synchronizing Two Conveyor Lines
	The dual-channel Laureate transmitter can measure the speed of conveyor lines by using the output of proximity switches which sense gear teeth or spokes of rotating drive wheels. Transmitting the speed ratio of two lines allows line speeds to be adjusted so that material arrives at work stations when needed.
Measuring Draw for Elongation
	Draw (Ch A / Ch B - 1) can be used to indicate the elongation of films compressed between rollers, the shrinkage films, and the RPM difference of rollers whose speed is varied to maintain tension. The high resolution of Laureate dual channel transmitters is ideal for comparison of rates that are close to each other.

Pinout
Laureate 4-20 mA Transmitter for Ratio, Product, Sum or Difference of 2 Inputs

Ordering Guide
Laureate 4-20 mA Transmitter for Ratio, Product, Sum or Difference of 2 Inputs
Click on the radio buttons to build a model number with pricing (shown below the Ordering Guide).

Quantity
Transmitter Type	LTA Laureate 4-20 mA Transmitter	$235
Main Board	8 Extended Main Board (required for arithmetic functions)	$40
Power	0 Isolated 85-264 Vac 1 Isolated 12-32 Vac or 10-48 Vdc	NC $30
Relay Output	0 None 2 Isolated Dual Solid State Relays	NC NC
Input Type	FR Dual-Channel Frequency.	NC
Accessories	CBL04 RS-232 cable, TA to computer or USB adapter CBL02 USB to RS-232 cable adapter	$19 $39