Totalizer for 0-1 mA, 4-20 mA or 0-10V Signals Modbus or Laurel ASCII Protocol Serial I/O Transmitter

Description

Analog Process Totalizing

Laureate TM Series, serial I/0, process signal input totalizing transmitters accept 0-1 mA, 4-20 mA or 0-10V signals from flow meters and other transducers, such as watt meters.

• With a Standard Main Board, the transmitter output can track rate (such as gallons per minute or watts) or totalized rate (such as gallons or kilowatt hours) whether the transducer output is linear or requires square root extraction (differential pressure flow transducers).
   

• With an Extended Main Board, the transmitter can provided by a curvilinear spline fit with up to 180 data points. It 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 process transmitters described in this page convert the full-scale 0-1 mA, 4-20 mA or 0-10 V analog input signal to a frequency of 10-110 kHz, which is converted internally to a 6-digit rate reading rate using inverse period timing and a calibrated quartz crystal time base. The analog-to-digital conversion is exceedingly accurate, ±0.005% of span ±1 count at 25°C. It is also fast, at 25 conversions per second. The full conversion accuracy is maintained in the serial output.

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 Laurel 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 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.