Quadrature Position or Rate Modbus or Laurel ASCII Protocol Serial I/O Transmitter

(Transmits accurate position or rate from quadrature encoders. DIN Rail mounted, digitally programmable.)
  • Selectable Modbus or Laurel ASCII protocol.
  • Programmable for position, angle or rate.
  • Quadrature count x1, x2 or x4.
  • Display refresh rate up to 25/s.
  • Isolated 5V, 10V or 15V dc excitation output.
  • Detachable screw clamp plug connectors.
  • Optional dual solid state relays for alarm or control.
  • Modbus RTU or ASCII modes, 2-wire connection, up to 247 digital addresses.
  • Accepts low-level differential or single-ended 5 V logic level outputs from shaft encoders.
  • Combined pulse rate to 250 kHz.
  • Zero channel input.
  • DIN rail mount package only 22.5 mm thick.
  • Easy setup using Laurel's PC-based Instrument Setup Software.
Position, Length or Angle Measurement
Laureate Modbus I/O quadrature transmitters accept the A & B signals from shaft encoders to provide a highly accurate reading of position, length, angle, or rate. The A & B quadrature signals are 90º out of phase, and their phase relationship determines whether up counts (+) or down counts (-) are produced.

One, two or four transitions may be counted at a maximum combined rate of 250 kHz and be scaled internally from -999,999 to +999,999. counts. The input circuitry which 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 current 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 meter setup choices.

 A zero index pulse, if available, is interpreted by the transmitter as corresponding to an integral number of revolutions of the shaft encoder. It is used by the transmitter to correct for any cumulative pulse count errors. Special circuitry corrects for width of the zero index pulse. A built-in isolated 5V, 10V or 15V dc excitation supply is available to power shaft encoders and eliminate the need for an external power supply.

Available for Totals or Rate
With the Standard main board, tthe transmitter totalizes the counts and then scales the total in software for display and control. A zero index signal can be added as a third input to the A & B signals.

With the Extended main board, the transmitter can can also output an analog signal that tracks scaled rate. For example, the output can track the speed of a moving slab or RPM of a roller. The output update rate for position or rate is normally set to a maximum of 25/sec, as determined by a user-programmable gate time.

Serial Data I/O & Programming
Laureate TM Series transmitters send data as a serial digital signal. RS485 or RS232 signal levels are jumper selectable and can each be associated with either the Modbus protocol or Laurel’s simpler Custom ASCII protocol.

Modbus protocol operation is fully compliant with the Modbus Over Serial Line Specification V1.0 (2002) for 2-wire, half-duplex connection. This includes RTU or ASCII modes, addressing of up to 32 devices per RS485 line without a repeater, and up to 247 digital addresses. Modbus operation allows devices by different manufacturers to be connected in parallel and be addressed using the same protocol.

Laurel’s 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’s datalogging software.

Transmitter programming is via the unit's three-terminal serial port using Laurel's PC-based Instrument Setup Software. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from Laurel (P/N CBL03). Laurel's serial output transmitters and meters can also be part of PC-based data logging systems using Laurel's Datalogging Software, which operates under the Laurel ASCII Protocol. A single software command switches between the Modbus and Laurel ASCII Protocols.

Transmitter Options

Options include dual solid state relays for local alarm or control and an isolated 4-20 mA or 10V (selectable) analog output, effectively providing a linearized analog transmitter output that tracks the reading that would be transmitted digitally. The analog output provides 12-bit (4096 step) resolution of the output span and is ultra-linear to within one bit. Its accuracy is ±0.05% of span for all signal types, except for AC rms, where accuracy is ±0.1%. Output isolation from signal and power grounds is provided by a separate on-board power supply, which can drive 20 mA into a 500 ohm load for 10V compliance. Output isolation eliminates problems caused by ground loops.

DIN Rail Mounting

Laureate transmitters are housed in a 35 mm DIN rail case that is only 22.5 mm (0.89") thick. Signal connections are via detachable screw clamp plug connectors.


Quadrature Inputs
Type Differential or single-ended quadrature
Transitions Monitored x1, x2 or x4
Max Pulse Rate 250 kHz at x1, 125 kHz at x2, 62.5 kHz at x4
Internal Counts -999999 to +999999
Position Error No error contributed by transmitter
Quadrature Position Mode
Zero Adjust -999999 to +999999
Span Adjuste 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
Serial I/O (standard)
Signal levels RS485 (default) or RS232 (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 RTU, Modbus ASCII, Laurel ASCII (selectable)
Devices on RS-485 Line 32 max without a repeater.
Modbus Addresses 247 max
Modbus Modes RTU or ASCII, 2-wire.
Modbus Compliance Modbus over Serial Line Specification V1.0 (2002).
Transducer Excitation Output (standard)
Jumper Selection 1 10V @ 60 mA, isolated to 50V from signal ground
Jumper Selection 2 5V @ 50 mA, isolated to 50V from signal ground
Jumper Selection 3 15V @ 60 mA, non-isolated
Dual Relay Output (optional)
Relay Type Two solid state relays, SPST, normally open, Form A
Load rating 120 mA at 130 Vac or 170 Vdc, 28 ohms series resistance
Analog Output (optional)
Output Levels 0-20 mA, 4-20 mA or  0-10 Vdc (selectable)
Compliance, 4-20 mA 10V ( 0-500 ohm load )
Compliance, 0-10V 2 mA ( 5 kOhm load )
Output Resolution 12 bits (4,096 steps)
Output Accuracy ±0.05% of output span
Output Isolation 250V rms working, 2.3 kV rms per 1 minute test
Power Input
Standard power 95-240V AC ±10% or 90-300V DC
Low power option 12-30V AC or 10-48V DC
Frequency DC or 47-63 Hz
Power Isolation 250V rms working, 2.3 kV rms per 1 min test.
Case Dimensions 120 x 101 x 22.5 mm
Case Mounting 35 mm rail per DIN EN 50022
Electrical Connections Detachable screw clamp plug connectors
Operating Temperature 0°C to 70°C
Storage Temperature -40°C to 85°C
Relative Humidity 95% at 40°C, non-condensing

Application Examples

Using Quadrature for Cutting to Length
Controlling the repetitive cutting of material to length is an excellent application of the Laureate quadrature transmitter.

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
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 can use its optional dual relay setpoint capability for closed loop control.
Using Quadrature to Monitor a Drilling Operation
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.
Pinout Laureate Serial Output Transmitter, Quadrature Input
(shown with optional analog output and dual relay output)
Quadrature Transmitter with Differential or Complementary Inputs
create facebook
5672 Bolsa Avenue Huntington Beach, CA 92649 - USA - Ph (714) 622-2000 - Fax (714) 622-2001