AC Phase Angle Input Modbus or Laurel ASCII Protocol Serial I/O Transmitter

(For angular phase offset in degrees of AC waveforms. DIN Rail mounted, digitally programmable.)
Common Features
  • Selectable Modbus or Laurel ASCII protocol.
  • Compliant with Laurel ASCII protocol (selectable).
  • Frequency from .005 Hz to 10 kHz.
  • 01% accuracy at AC line frequency.
  • Inputs from NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC inputs up to 250 Vac.
  • 5V, 10V or 15 V dc excitation output to power sensors.
  • Detachable screw clamp plug connectors
  • Modbus RTU or ASCII modes, 2-wire connection, up to 247 digital addresses.
  • Transmits phase angle between two AC waveshapes of similar period.
  • Resolution of 1°, 0.1° or 0.01°
  • Converts phase input to six-digit reading:
     - Digital span adjust from 0 to ±999,999.
     - Digital zero adjust from -999,999 to +999,999.
  • Triggers on positive or negative pulse edges.
  • DIN rail mount package only 22.5 mm thick.
  • Easy setup using Laurel's PC-based Instrument Setup Software.
 The serial output of Laureate AC phase angle transmitter indicates the lead or lag in degrees from 0° to 360° between two periodic signals having the same period. In the illustration to the left, phase angle is 360*P1/P. The signals are applied to the Channel A and B inputs of the Laureate dual-channel pulse input signal conditioner board.

Phase angle measurement is commonly used with AC power from 50 Hz to 400 Hz. Phase angle needs to be set to zero to synchronize AC generators. It also applies to the triggering of SCRs and Triacs for power control. The phase angle between AC current and voltage determines power factor. The Laureate phase angle meter and transmitter provide exceptionally fast response and high accuracy for low frequencies, such as AC line frequency.

Phase angle measurement with the Laureate phase angle meter or phase angle transmitter requires that two signals with identical periods be applied to Channels A and B. A display from -180° to +180° is obtained by timing the rising edge of one channel and the falling edge of the other channel, and programming a 180° offset. A resolution of 1°, 0.1° or 0.01° is selectable. Accuracy is 0.01% up to 100 Hz, 0.1% at 1 kHz, and 1% at 10 kHz.

Phase angle is determined by timing crystal clock pulses over a specified gate time which is selectable from 10 ms to 199.99 s. By selecting the minimum gate time of 10 ms, the update rate can be up to 20/s for 50/60 Hz AC line frequency. Improved accuracy is obtained by making the gate time long enough so that multiple cycles can be averaged.

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 I/O 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.


Pulse Input
Types AC, pulses from NPN, PNP transistors, contact closures, magnetic pickups.
Signal Ground Common ground for channels A & B.
Minimum Signal Nine ranges from (-12 to +12 mV) to (+1.25 to +2.1V).
Maximum Signal 250 Vac
Maximum Frequency 1 MHz, 30 kHz,  250 Hz (selectable).
Contact Debounce 0, 3, 50 ms (selectable).
Phase Angle Operation
Item Transmitted Phase angle difference between two waves of same period
Digital Resolution 6 digits
Transmitted Units 1°, 0.1°, 0.01°
Frequency Range 0.005 Hz to 10 kHz
Accuracy 0.01°, 0.005 Hz to 100 Hz; 0.1° at 1 kHz, 1° at 10 kHz
Maximum Timing Interval 200 s
Update Rate
Conversion Interval Gate time + 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
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 Protocol 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 Example

Using Laureate Meters, Counters and Transmitters to Synchronize Motor Generators
Synchronization of two motor generators requires that the two frequencies be identical, that the lines be in phase, and that the line voltages be close to each other. In this illustration, a single Laureate dual channel counter (or frequency transmitter) measures both frequencies to six-figure accuracy in a few line cycles. Another Laureate dual channel counter (or phase transmitter) measures phase angle to 0.1° resolution. Two Laureate AC RMS Voltmeters, which offer ranges of 200.00 V and 600.0 V, are used to display the two RMS voltage to 0.1% accuracy.
5672 Bolsa Avenue Huntington Beach, CA 92649 - USA - Ph (714) 622-2000 - Fax (714) 622-2001