Features
- Accepts low-level differential or single-ended 5V logic level signals from shaft encoders, linear encoders, incremental encoders or optical encoders
- Programmable for position, angle or rate
- Maximum pulse rates of 250 kpulses/sec at X1, 125 kpulses/sec at X2, 62.5 kpulses/sec at X4
- Zero channel input
- 4-20 mA, 0-20 mA, 0-10V or -10V to +10V transmitter output, (isolated)
- Analog output resolution 0.0015% of span, accuracy ±0.02% of span
- RS232 or RS485 serial data, Modbus or Laurel ASCII protocol (isolated)
- Dual 120 mA solid state relays for alarm or control (isolated)
- 5V, 10V, 12V, or 24V dc transducer excitation output (isolated)
- Power 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac (isolated)
- DIN rail mount housing, 22.5 mm wide, detachable screw-clamp connectors
- Operating temperature from -40°C to 70°C (-40°F to 158°F)
Optional - Extended supports a range of ±999,999 for reading bidirectional rate or position from shaft encoders, though not simultaneously
Certificates of Compliance
The Laureate 4-20 mA, 0-20 mA, 0-10V or -10V to +10V and RS232/RS485 output transmitter for quadrature accepts A & B quadrature encoder signals to provide an analog output that tracks position, length, angle, or rate. The A & B quadrature signals are 90° out of phase, and their phase relationship determines whether up counts (+) or down counts (-) are produced.
One, two or four quadrature transitions may be counted at a maximum combined rate of 250 kHz and be scaled internally to ±999,999 counts. The input circuitry may be jumpered for either single-ended input signals or for balanced line driver signals. Anti-jitter circuitry eliminates errors produced by vibration of the encoder. In the event of a power failure, the latest total may be stored in non-volatile memory and can be used as the starting point for counting when power resumes. Power fail or zero index capabilities are alternate transmitter setup choices.
A zero index pulse, if available, is interpreted as indicating a zero reference for an integral number of revolutions of a rotary shaft encoder or as the home position of a linear encoder. It is used by the transmitter for initializing and to correct for any cumulative pulse count errors. Special circuitry corrects for width of the zero index pulse.
Bidirectional Total or Rate
- With the Standard main board, the transmitter totalizes the quadrature counts and then scales the total in software for the output. A zero index Z signal can be added as a third input to the A & B signals. The analog output is generated by an ultra-linear 16-bit (65,536 step) digital-to-analog converter (DAC) for 0.02% output accuracy.
- With the Extended main board, the transmitter can be programmed to output either total or rate or rate. For example, the output can track the speed of a moving slab from the RPM of a roller. The update rate for rate is a programmed gate time + 30 ms + 0-2 pulse periods.
Unidirectional Total and Rate
If the counts are only for one direction, for example, for extrusions measured by an encoder wheel, only the encoder's "A" channel can be used and be output to an Extended Laureate totalizer transmitter. This model accommodates very high pulse rates up to 1 MHz, and unlike the quadrature transmitter, it can simultaneously track rate and total.
The optional extended Laureate computer board can display rate based on successive readings. It also allows exceptionally accurate custom curve linearization, for example to read out liquid volume or rate of flow in a horizontal cylindrical tank based on level reported by a 4-20 mA transmitter. For setup, up to 180 data points can be input into a computer spreadsheet or text file by the user. The computer then calculates spline-fit segments, which are downloaded into the transmitter.
Exceptional Accuracy and Stability. Laureate 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 a 60 Hz signal, the update rate would be 20 per second. Such fast update rates are ideal for alarm and control.
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.
All signal conditioner board ranges are factory-calibrated, with calibration factors for each range securely stored in an onboard EEPROM. These factors can be scaled via software to accommodate external shunts, enabling field replacement of signal conditioner boards without necessitating recalibration of the associated transmitter. For optimal accuracy, factory recalibration is recommended annually. All Laurel Electronics instruments undergo factory calibration using the industry-leading Fluke calibrators, which are recalibrated yearly and certified traceable to national standards, ensuring the highest level of precision and reliability.
Laureate Transmitters are easily programmed with Laurel’s free Instrument Setup Software, downloadable from our website and compatible with Windows PCs, requiring a data interface board for setup.
Standard Features of Laureate LT Transmitters Include:
- Serial communications output, (isolated), RS232 or RS485 (half or full duplex), jumper selectable. 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 is simpler than the Modbus protocol and is recommended when all devices are Laureates.
- 4-20 mA, 0-10V or -10V to +10V analog transmitter output, (isolated), jumper-selectable and user scalable. All selections provide 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. Note that Ethernet data I/O is provided by Laurel's LTE series transmitters.
- Dual-channel pulse inputs for voltage signals, NPN or PNP proximity switches, contact closures, magnetic pickups or flow meters.
- Dual solid state relays, (isolated), for alarm or control. Rated 120 mA at 130 Vac or 170 Vdc.
- Selectable transducer excitation output, (isolated), user selectable 5V@100 mA, 10V@120 mA, 12V@100 mA, or 24V@50 mA.
- Power 85-264 Vac, (isolated), low-voltage 10-48 Vdc or 12-32 Vac power is optional.
Digital signal filtering modes can be selected to ensure stable readings in electrically noisy environments.
- An unfiltered selection provides true peak and valley readings and aids in control applications.
- A batch average filter selection averages each 16 conversions.
- An adaptive moving average filter selection provides a choice of 8 time constants from 80 ms to 9.6 seconds. When a significant change in signal level occurs, the filter adapts by briefly switching to the shortest time to follow the change, then reverts back to its selected time constant. An Auto setting selects the time constant selection based on signal noise.
Peak and valley values are automatically captured. These may be displayed via Laurel's free Instrument Setup Software, which runs on a PC under MS Windows or can be transmitted as serial data.
Two control inputs (CMOS/TTL levels, logic 0 = tied to digital ground, logic 1 = open) or dry contacts that can be set to control / activate 14 transmitter commands.
An (isolated) 5, 10, 12, or 24 Vdc excitation output is standard to power transducers or two-wire transmitters. Ratiometric operation, which automatically compensates for changes in the applied excitation, is jumper selectable for applications, such as bridges, where the signal to be measured is proportional to the excitation level.
LT series DIN rail Transmitters & signal conditioners can be interfaced to a wide range of sensors and transducers using one of seven available plug-in signal conditioner boards. The transmitters duplicate the high performance (high accuracy, high read rate) and extensive programmable features of Laureate 1/8 DIN digital panel meters, counters and timers. They utilize the same signal conditioners boards, much of the same firmware, and Laurel's free Windows-based Instrument Setup Software. They come in a compact DIN rail mount package with detachable screw-clamp connectors for easy wiring.
The LT series Transmitters accessible from this page include a 4-20 mA, 0-20 mA, 0-10V, or -10V to +10V analog output (isolated, user selectable), an RS232 or RS485 serial data interface (isolated, user selectable), and dual 120 mA solid state AC/DC relays (isolated). An (isolated) 5, 10, 12, or 24 Vdc transducer excitation output is included with all models other than those with a temperature or AC RMS signal conditioner.
Connecting Laureate LT Transmitters to a Local Area Network (LAN)
Up to 30 Laureate LT Transmitters and/or Digital Panel Meters can be configured for RS485 and daisy-chained to an LT Transmitter for seamless LAN integration. Alternatively, Laurel LTE series Ethernet transmitters can connect directly to a LAN via an Ethernet cable. Setup for both configurations is streamlined using Laurel’s free Instrument Setup Software, which simplifies node discovery and transmitter configuration.
Flexible Communication Options for LT Transmitters
Laureate Transmitters can be equipped with Laurel communication boards to support various interfaces and protocols. These include serial interfaces with ASCII or Modbus RTU protocols, and Ethernet interfaces with web access, ASCII, or Modbus TCP/IP protocols, ensuring versatile connectivity for your commercial applications.
| LT Transmitter Signal Input & Function | Model Series | Analog Output | RS232 & RS485 | Dual Relays | |
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| 1 | DC Input Voltage and Current | LT-DC |  |
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| 2 | AC RMS Voltage or Current | LT-RMS | |
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| 3 | Process Voltage or Current | LT-P | |
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| 4 | Weighing Applications | LT-WA | |
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| 5 | Load Cell & Microvolt Signals | LT-WM | |
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| 6 | Thermocouple (Types J, K, T, E, N, R, S) | LT-TC | |
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| 7 | RTD Temperature | LT-RTD | |
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| 8 | Resistance in Ohms | LT-R | |
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| 9 | Frequency, Rate, Speed | LT-FR | |
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| 10 | Pulse Input Totalizer | LT-FR | |
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| 11 | Process Signal Totalizer | LT-VF | |
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| 12 | Sum, Difference, Ratio, Product of 2 Inputs | LT-FR | |
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| 13 | Batch Controller Pulse Input | LT-FR | |
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| 14 | Batch Controller Analog Input | LT-FR | |
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| 15 | On/Off Duty Cycle | LT-FR | |
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| 16 | Stopwatch Timing for Single Events | LT-FR | |
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| 17 | Average Time of Periodic Events | LT-FR | |
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| 18 | AC Phase Angle and Power Factor | LT-FR | |
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| 19 | Quadrature Position or Rate | LT-QD | |
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Laureate 4-20 mA & RS232/RS485 Data Transmitters for Position or Rate from Quadrature Encoders
| Quadrature Inputs | ||||
|---|---|---|---|---|
| Type | Differential or single-ended quadrature | |||
| Transitions Monitored | x1, x2 or x4 | |||
| Max Pulse Rate | 250 kpulses/sec at X1, 125 kpulses/sec at X2, 62.5 kpulses/sec at X4 | |||
| Internal Counts | -999999 to +999999 | |||
| Position Error | No error contributed by transmitter | |||
| Differential High Threshold | +200 mV | |||
| Differential Low Threshold | -200 mV | |||
| Differential Limits | -11V to +14V | |||
| Single-Ended High Voltage | 2.5V to 10V | |||
| Single-Ended Low Voltage | -1V to +1V | |||
| Input Resistance, Typ. | 17 kOhm | |||
| Recalibration: All ranges are calibrated at the factory. Recalibration is recommended every 12 months. | ||||
| Quadrature Position Mode | ||||
| Zero Adjust | -999999 to +999999 | |||
| Span Adjust | 0 to ±999999 | |||
| Quadrature Rate Mode | ||||
| Conversion Technique | Inverse period | |||
| Output Update Rate | 30 ms + 0-2 signal periods | |||
| Gate time | Selectable 10 ms to 199.99 s | |||
| Time Before Zero Output | Selectable 10 ms to 199.99 s | |||
| Time Base Accuracy | Calibrated to ±2 ppm | |||
| Zero Adjust | -999999 to +999999 | |||
| Span Adjust | 0 to ±999999 | |||
| Analog Output (standard) | ||||
| Output Levels | 4-20 mA, 0-20 mA, 0-10 Vdc, -10 to +10Vdc (user selectable) | |||
| Compliance, 4-20 mA | 10V (0-500 ohm load) | |||
| Compliance, 0-10V | 2 mA (5 kOhm load) | |||
| Output Resolution | 16 bits (65,536 steps) | |||
| Output Accuracy | ±0.05% of output span | |||
| Output Update Rate | 25/sec max | |||
| Output Isolation | 250V rms working, 2.3 kV rms per 1 minute test | |||
| Serial Data Output (standard) | ||||
| Signal Types | RS232 or RS485 (half or full duplex), jumper selectable | |||
| Data Rates | 300, 600, 1200, 2400, 4800, 9600, 19200 baud | |||
| Output Isolation | 250V rms working, 2.3 kV rms per 1 min test | |||
| Serial Protocols | Modbus TCP, Modbus RTU, Modbus ASCII, Custom ASCII | |||
| Modbus Compliance | Modbus over Serial Line Specification V1.0 (2002) | |||
| RS232/RS485 Connector | Screw terminals for easy daisy chaining | |||
| Digital Addresses | 247 for Modbus, 31 for Custom ASCII | |||
| Dual Relay Output (standard) | ||||
| Relay Type | Two solid state relays, SPST, normally open, Form A | |||
| Load Rating | 120 mA at 140 Vac or 180 Vdc | |||
| Excitation Output (standard) | ||||
| 5 Vdc | 5 Vdc ± 5%, 100 mA (jumper selectable) | |||
| 10 Vdc | 10 Vdc ± 5%, 120 mA (jumper selectable) | |||
| 12 Vdc | 12 Vdc ± 5%, 100 mA (jumper selectable) | |||
| 24 Vdc | 24 Vdc ± 5%, 50 mA (jumper selectable) | |||
| Output Isolation | 50 Vdc from signal ground | |||
| Power Input | ||||
| Standard Power | 85-264 Vac or 90-300 Vdc | |||
| Low Power Option | 10-48 Vdc or 12-32 Vac | |||
| Power Frequency | DC or 47-63 Hz | |||
| Power Isolation | 250V rms working, 2.3 kV rms per 1 min test | |||
| Power Consumption at 24V | 1.5W typical, 3W with max excitation output | |||
| Environmental | ||||
| Operating Temperature | -40°C to 70°C (-40°F to 158°F) | |||
| Storage Temperature | -40°C to 85°C (-40°F to 185°F) | |||
| Relative Humidity | 95% at 40°C, non-condensing | |||
| Cooling Required | Mount transmitters with ventilation holes at top and bottom. Leave 6 mm (1/4") between transmitters, or force air with a fan. | |||
| Mechanical | ||||
| Enclosure | Rugged black polycarbonate housing material | |||
| Mounting | 35 mm rail per DIN EN 50022 | |||
| Dimensions | 129 x 104 x 22.5 mm case | |||
| Connectors | Detachable screw clamp connectors meet VDE / IEC / UL / CSA standards. RJ45 jack for Ethernet | |||
| Tightening Torque | Screw terminal connectors: 5 lb-in (0.56 Nm) | |||
| Weight | Complete transmitter: 183 g (6.5 oz) | |||
| Replacement Case Screws | ||||
| Size | 6 | |||
| Thread Pitch | 6-19 | |||
| Length | 1/2" | |||
| Head Style | Pan Head | |||
| Drive Style | Phillips | |||
| Head Diameter | 0.256-0.270 | |||
| Head Height | 0.087-0.097 | |||
| Full/Partial Thread | Full | |||
| Drive Size | 2 | |||
| Material | Steel | |||
| Finished | Black Oxide | |||
| General | ||||
| Programming | Utilize Laurel's free Instrument Setup Software, which runs on a PC under MS Windows. | |||
| Security | Lockout options available using Laurel's free Instrument Setup Software. | |||
| Warranty | 3 years parts & labor | Recalibration: All ranges are calibrated at the factory. Recalibration is recommended every 12 months. | ||
Transmitter Pinout
Free Instrument Setup Software for Series 2 Laureates
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| 1/8 DIN Digital Panel Meters | DIN Rail Transmitters |
Free Downloadable Windows-based Instrument Setup (IS) software (Data Interface Board Required) for use with our programmable Digital Panel Meters, Scale Meters, Counters, Timers, Remote Displays, and Transmitters, are an easy method to set up Laureate 1/8 DIN digital panel meters, counters, timers, remote displays, and DIN-rail transmitters, as explained in the Instrument Setup Software Manual. Laureate 1/8 DIN instruments can also be set up from the front panel, as explained in their respective Owners Manuals. Instrument Setup software is of benefit whether or not the PC is connected to the instrument.
- When the PC is connected to the instrument, Instrument Setup software can retrieve the setup file from the instrument or open a default setup file or previously saved setup file from disk View Setup, then provides graphical user interface (GUI) screens with pull-down menus applicable to input, display, scaling, filtering, alarms, communications, analog output, and front panel lockouts. Fields that are not applicable to the instrument as configured are either left out or grayed out. Clicking on any item will bring up a detailed Help screen for that item. After editing, the setup file can be downloaded, uploaded to the instrument, or saved to a disk. The same setup file can then be downloaded into multiple instruments.
- When the PC is not connected to the instrument, the above GUI screens can be used to set up a virtual instrument. The setup file can then be saved to disk. Switching toView Menu then brings up a screen with the required front panel programming steps. This view can be printed out for use at the instrument site and to serve as a hard copy record.
Download Free Instrument Setup Software
Installation
Set User Account Control (UAC) of MS Windows to "Never notifiy me" so that Instrument Setup Software can create directories. The UAC change screen can be reached as follows:
- Under Windows 7, click on the Windows Start button in the lower left of the desktop and enter "UAC" in the search field.
- Under Windows 8, navigate to Control Panel, then to the "User Accounts and Family Safety" section, and click on "Change User Account Control Settings."
- Under Windows 10, click on the Windows Start button in the lower left of the desktop, then on "Settings", and enter "UAC" in the search field.
- Reboot your computer for the changed UAC setting to take effect.
RJ11-to-DB9 cable with rear view of DB9 connector to PC
RS232 cable, meter to PC, P/N CBL01
Laureate 1/8 DIN Laureate instruments must be equipped with a serial communications board and be connected to the computer via a serial communications cable. The connection can be via RS232, RS485, USB or Ethernet. Following setup, the serial communications board may be removed from the instrument if desired. The wiring of the RS232 cable is illustrated above with end views of the two connectors.
Laureate LT Series transmitters come standard with a 3-wire serial interface, which can be jumpered for RS232 or RS485.
Laureate LTE Series transmitters come standard with an Ethernet interface.
Meter Setup Screens
Click on any of the reduced screens below for a full-size screen view, then click on the Back button of your browser to return to this page. The screens examples below are for a fully-loaded Series 2 Digital Panel Meter (DPM), which is connected to the PC via RS232. If the meter is a Series 1 meter (pre-2007), this is sensed by the software, and somewhat different screens are brought up. Please see Series 1 setup screens.
Welcome Screen
From the computer desktop, click on Start > Programs > IS2 > IS2. Or click on the IS icon on your desktop. This splash screen will be displayed for three seconds. The software revision number is in the lower right.
Communications Selection Screen
Specify your desired communication protocol and the serial communications bus type, which should match the jumper setup of the instrument. Select None if the PC is not connected to the instrument.
Establish Communications Screen
If you selected RS-232, you will be asked to specify the PC Com Port and Baud Rate, which should match the jumper setup of the instrument. Click on Establish. With the right settings, the Communications Established field will light up in green, and the Meter Type will be recognized. If so, click onMain Menu.
Main Menu Screen
Click on File > Default Setup to retrieve the default setup file from disk for your type of meter. Click on File > Open Setupto retrieve a previously saved setup file from disk or on File > Save Setup to save your edited setup file to disk. Click onDPM > Get Setup to retrieve the setup file from your meter or on DPM > Put Setup to download your edited setup file into the meter.
DPM Input + Display Setup Screen
From the Main Menu, click on View > Setup, then on theInput+Display tab. You can now specify the meter hardware, signal type, display mode, and functions of control inputs A and B. Clicking on any item brings up a pull-down menu with the available choices.
DPM Scaling Setup Screen
Click on the Scaling tab, which provides three scaling methods to relate the signal to the displayed reading: 1) Scale and Offset method, 2) Coordinates of two points method, and 3) Reading Coordinates of Two Points method. The last method uses actual high and low signals, and the computer will prompt you.
DPM Filter Setup Screen
Click on the Filter tab, which allows you to specify the digital filter time constant (if any), the adaptive filter threshold, and whether Peak / Valley values are filtered or unfiltered. As for all setup screens, clicking on the F1 key while an item is highlighted brings up a Help screen for that item, as illustrated.
DPM Relay Alarms Setup Screen
Click on the Relay Alarms tab, which allows you to set up Alarms 1 and 2 for the optional dual relay output board. Clicking on any of the four numeric fields changes these to green and brings up a special field to enter the desired numeric value, which is tied to the displayed reading.
DPM Communications Setup Screen
Click on the Communications tab so set up serial communications. In particular, you can special the Serial Protocol and the meter address if multiple meters are to be addressed on the same serial data line.
DPM Analog Output Setup Screen
Click on the Analog Out tab so set up the optional analog output board. Three output ranges are selectable, the endpoints of which can be tied to user-specified High and Low readings.
DPM Lockouts Setup Screen
Click on the Lockouts tab to check off menu items which will no longer be accessible from the front panel of the meter. This will simplify meter operation and prevent unintended setup changes.
Meter Setup Utilities
DPM Front Panel Setup Screen
As an aid to programming the meter from the front panel when a serial connection is not available, you can return to the Main Menu and click on View > Menu. The required sequence of front panel screens will then be displayed. Click on any step in the sequence for the meaning of each digit, as illustrated for the FILtEr step. For a hardcopy, simply press on Print.
DPM Jumper Setup Screen
Specify your desired communication protocol and the serial communications bus type, which should match the jumper setup of the instrument. Select None if the PC is not connected to the instrument.
DPM Jumper Setup Screens
Click on any of the displayed plug-in boards, and you will be presented with the jumper positions and electrical connections for your selected board. This minimizes the need to refer to the printed manual.
DPM Commands Screen
This page allows you set up external input, serial communications, an analog output proportional to the display (optional), and lockouts for Laureate digital counters. The grayed out area at the top right of the screen applies to Laureate remote displays.
Graphical Output Screens (not available with Ethernet)
From the Main Menu, click on Readings if your PC is connected to the meter. A pull-down menu then offers three choices: List, Plot and Graph.
- List presents the latest readings in a 20-row by 10-column table. Press Pause at any time to freeze the display. This is one method to capture peak readings.
- Plot generates a plot of readings vs. time in seconds. It effectively turns the DPM-PC combination into a printing digital oscilloscope.
- Graph generates a histogram where the horizontal axis is the reading and the vertical axis is the number of occurrences of readings. The display continually resizes itself as the number of readings increases.
DPM Calibration Screens
Click on the Scaling tab, which provides three scalClick on the Scaling tab, which provides three scaling methods to relate the signal to the displayed reading: 1) Scale and Offset method, 2) Coordinates of two points method, and 3) Reading Coordinates of Two Points method. The last method uses actual high and low signals, and the computer will prompt you.
Frequency Meter Calibration Screen
Calibration of the quartz crystal of the Laureate frequency meter requires the input of a known frequency from a calibrator. Apply the frequency, then enter the frequency in Hertz. Calibration will be automatic, with storage of the calibration factor stored in non-volatile memory.
Dimensions
Dimensioned CAD assembly drawings in EPRT, STEP, x_t, .dwg, pdf file formats: Laureate-transmitter-case.zip (zipping prevents browser from opening CAD files as text files).
| Using Quadrature for Cutting to Length | |
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Controlling the repetitive cutting of material to length is an excellent application of a Laureate quadrature transmitter or Laureate quadrature meter. The quadrature encoder shares the shaft of a sensing wheel, whose rotation corresponds to lineal displacement of material. The transmitter compares the displacement reading against setpoint information, and then uses its dual relays to first slow down and then cut the material. |
| Using Quadrature for X-Y Positioning | |
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Accurate X-Y position or rate can be obtained from two shaft encoders, which convert linear position to quadrature signals as a shaft turns. In addition to serving as a transmitter, each Laureate transmitter or meter can use its optional dual relay setpoint capability for closed loop control. |
| Using Quadrature to Monitor a Drilling Operation | |
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Quadrature can be used to track position and vertical drilling speed of the bit in an oil drilling operation. A shaft encoder is rotated by a cable that moves with the drilling shaft. In this application, the same encoder signal is applied to a Laureate quadrature transmitter for position, and to a second quadrature transmitter for rate. Both transmitters can send a 4-20 mA signal to a control room and be alarmed. In this application, quadrature provides much higher immunity to noise and jitter than a magnetic pickup. |
CAL-Digital
Certificate of Calibration
$65.00
CBL02
USB-to-RS232 Adapter Cable
$47.00
CBL04
RS232 Cable for LT Transmitters
$47.00CBL12
12-foot Power Cable
$47.00CBL6
6-foot Power Cable
$41.00What Is the LT DIN Rail Digital Transmitter for Quadrature Encoder Input and Bidirectional Position or Rate?
Position and rate measurements from a rotating or linear encoder need to know direction, not just speed — a shaft turning forward and one turning backward look identical to a simple pulse counter unless the signal itself carries direction information. This LT DIN Rail Transmitter reads A and B quadrature encoder signals, which are 90° out of phase specifically so their relative phase relationship determines whether the count goes up or down, and converts that into an isolated 4-20 mA output and digital serial data tracking position, length, angle, or rate.
X1, X2, or X4 Transition Counting
The transmitter can count one, two, or four quadrature transitions per encoder cycle, at a maximum combined rate of 250 kHz, scaling internally to ±999,999 counts. Counting more transitions per cycle (X4 vs. X1) increases resolution from the same physical encoder at the cost of a lower maximum pulse rate — 250 kpulses/sec at X1, down to 62.5 kpulses/sec at X4.
Differential or Single-Ended Input
Input circuitry can be jumpered for either single-ended input signals or balanced differential line driver signals, matching whichever type of encoder is already installed. Anti-jitter circuitry specifically corrects for errors that vibration of the encoder would otherwise introduce into the count.
Zero Index and Power-Fail Memory
A zero index pulse, when available from the encoder, gives the transmitter a defined reference point — either a fixed position for an integral number of rotary shaft revolutions, or the home position of a linear encoder — used both to initialize the count and to correct any cumulative pulse count error over time. Separately, the transmitter can store its latest total in non-volatile memory in the event of a power failure, so counting resumes from that stored total rather than restarting from zero when power returns; power-fail memory and zero-index referencing are alternate setup choices rather than both being used simultaneously.
Bidirectional Total or Rate — But Not Simultaneously
With the Standard main board, the transmitter totalizes quadrature counts and scales that total for output, with an optional third zero-index (Z) input alongside the A and B signals. With the Extended main board, the transmitter can instead be programmed to output rate — for example, tracking the speed of a moving slab from the RPM of a roller — but position/total and rate are not available simultaneously on this quadrature model, unlike some other LT Series variants. For unidirectional counting only (such as extrusion length from an encoder wheel), only the encoder's A channel is needed, feeding into an Extended totalizer transmitter that supports pulse rates up to 1 MHz and can track rate and total simultaneously.
Named Applications
- Cutting Material to Length — a quadrature encoder shares the shaft of a sensing wheel whose rotation corresponds to linear material displacement; the transmitter compares that displacement against a setpoint and uses its dual relays to first slow, then cut the material at the correct length.
- X-Y Positioning — two shaft encoders convert linear position on each axis into quadrature signals, with each transmitter's optional dual relay setpoint capability supporting closed-loop control on its axis.
- Monitoring a Drilling Operation — a shaft encoder rotated by a cable moving with the drilling shaft feeds the same signal to one quadrature transmitter configured for position and a second configured for rate, both sending 4-20 mA to a control room; quadrature's higher noise and jitter immunity compared to a magnetic pickup matters specifically in this kind of harsh drilling environment.
Industries That Use This Transmitter
- Manufacturing and Material Processing — cutting material to length and other length/position control tied directly to encoder-measured displacement.
- Oil and Gas — drilling depth and rate monitoring using quadrature's noise immunity in electrically harsh environments.
- Machine Building and Robotics — X-Y and multi-axis positioning feedback for closed-loop motion control.
- Packaging and Converting — web and roll-fed material tracking where accurate, direction-aware length measurement matters.
- Test and Measurement — precision position or rate feedback from shaft or linear encoders in lab and calibration setups.
Conclusion
The LT DIN Rail Digital Transmitter for quadrature encoder input gives a panel builder a direction-aware way to convert shaft or linear encoder signals into position, length, angle, or rate — with the input flexibility to match differential or single-ended encoders, the resilience of anti-jitter circuitry and power-fail memory, and documented use in applications from length cutting to drilling depth monitoring where knowing direction, not just speed, is the whole point.
Quadrature Encoder Transmitter Frequently Asked Questions
Why does the A and B signal's 90° phase relationship determine count direction?
Which signal (A or B) leads the other by 90° depends on which direction the encoder shaft is turning; the transmitter reads this leading/lagging relationship to determine whether to increment or decrement the count, which is what allows it to distinguish forward from reverse motion using only two signals.
When would I choose X4 counting instead of X1?
X4 counting extracts four times the resolution from the same physical encoder by counting every transition of both A and B signals rather than just one edge per cycle, useful when finer resolution is needed and the resulting lower maximum pulse rate (62.5 kpulses/sec vs. 250 kpulses/sec at X1) still exceeds what the application's actual encoder speed requires.
Why can't this transmitter output rate and position/total simultaneously?
The Extended main board's processing is configured for one output mode at a time on this model — either bidirectional total/position or bidirectional rate — unlike some other LT Series variants that support simultaneous rate and total; if both are needed at once from the same encoder, the documented drilling application uses two separate transmitters, one configured for each.
What does the zero index pulse actually correct for?
Over very long runtimes, cumulative small errors (from noise, jitter, or missed transitions) could theoretically drift the count away from true position; a zero index pulse gives the transmitter a periodic absolute reference point to re-synchronize against, preventing that drift from accumulating indefinitely.
Should I use power-fail memory or zero index referencing?
These are documented as alternate setup choices rather than complementary features used together — power-fail memory preserves the last count through a power interruption, while zero-index referencing re-establishes an absolute reference each cycle; which one fits depends on whether the application can tolerate resuming from a stored (but potentially drifted) count versus needing periodic absolute re-referencing.
What's the practical difference between differential and single-ended encoder inputs?
Differential (line driver) signals use a matched positive/negative pair per channel and are inherently more resistant to picking up electrical noise over longer cable runs, while single-ended signals use a single wire referenced to ground per channel and are simpler but more susceptible to noise; the transmitter's input can be jumpered to match whichever type the connected encoder actually outputs.
Why is quadrature specifically noted as more noise-immune than a magnetic pickup in the drilling application?
A magnetic pickup produces a single analog-like pulse train that noise can more easily corrupt or miscounted, while quadrature's two-channel, phase-relationship-based encoding gives the transmitter more information to reject spurious noise and jitter, which is documented as specifically valuable in electrically harsh environments like drilling rigs.
Does anti-jitter circuitry eliminate all vibration-related count errors?
It's documented specifically to eliminate errors produced by encoder vibration, addressing that particular noise source; it isn't described as a general-purpose noise filter for other error sources like electrical interference on the signal lines, which are instead addressed through proper shielding and, where applicable, differential signaling.
Can multiple quadrature transmitters be networked together?
Yes — up to 30 LT Transmitters and/or Digital Panel Meters can be daisy-chained on RS485 for LAN integration, or a high-speed Ethernet or WiFi communication board can be used instead for network connectivity.
Quadrature Encoder Transmitter Questions From the Field
My position count seems to drift slightly over long runs even though nothing physically moved unexpectedly — what should I check?
Gradual drift over long runtimes without an obvious cause is exactly what zero index referencing is meant to correct; if the encoder has a zero index (Z) signal available but it isn't currently wired in or enabled, adding it is the standard fix rather than suspecting a transmitter fault.
My cut-to-length application occasionally cuts short or long by a repeatable amount — what's the likely cause?
A consistent, repeatable offset often points to mechanical slippage between the sensing wheel and the material (rather than an encoder or transmitter fault), since any slip between the wheel and material directly translates into a proportional length measurement error; checking wheel-to-material contact and any slippage is the standard first step.
My count direction seems reversed from what I expect — what should I check?
A reversed count direction typically points to the A and B channel wiring being swapped relative to what the transmitter's configuration expects, since swapping which channel leads the other inverts the up/down determination; checking A/B wiring against the encoder's documentation is the standard first step.
My reading is unstable specifically when the encoder or its mounting vibrates — is that expected to be fully eliminated?
Anti-jitter circuitry is documented to address errors from encoder vibration specifically, but severe or unusual vibration beyond typical operating conditions could still affect readings; checking mechanical mounting and vibration isolation is worth investigating if instability persists despite the anti-jitter circuitry being active.
My power-fail total doesn't match where I expect the count to resume — why?
If any physical movement occurred during the power outage itself (which the transmitter obviously can't count while unpowered), the stored total will be accurate to the moment power was lost but won't reflect movement during the outage; this is an inherent characteristic of power-fail memory rather than a fault, and zero-index referencing (if available) can help re-establish an accurate absolute position after power resumes.
Can I use a single-ended encoder with a transmitter jumpered for differential input, or vice versa?
The input jumpering needs to match the actual encoder signal type; a mismatch between the jumper configuration and the physical signal type is a common cause of erratic or completely absent counting, so verifying the jumper setting matches the connected encoder's actual output type is a standard troubleshooting step.
My two transmitters in the position+rate drilling-style setup show inconsistent readings from the same encoder signal — what should I check?
Since both transmitters read the identical physical signal but are configured for different output modes (position vs. rate), confirming each is genuinely configured for its intended mode — rather than both accidentally configured the same way — is the first step before suspecting a wiring or signal-splitting issue.
