MLT-R | 4-20 mA & Serial Data Output | Resistance in Ohms | DIN Rail Transmitter

The Micron Resistance Transmitter is ideal for high-speed, high-accuracy resistance measurements in a production environment, such as contact resistance measurements. It is factory calibrated for five jumper selectable resistance ranges from 20.000 ohm to 200.00 kohm. Factory-special, fixed ranges of 2.0000 ohm or 2.0000 Mohm are also available. Accuracy is an exceptional ±0.01% of reading ± 2 counts. Resolution is one part in 20,000. In the 2 ohm range, resolution is 0.1 milliohm for contact resistance measurements.

Transmitter connections can be via 2, 3 or 4 wires. With 4-wire hookup, 2 wires are used for excitation and two separate wires are used to sense the voltage across the resistance to be measured, thereby eliminating any lead resistance effects. With 3-wire hookup, the transmitter senses the combined voltage drop across the RTD plus two excitation leads. It also senses the voltage drop across one excitation lead, and then subtracts twice this voltage from the combined total. This technique effectively subtracts the lead resistance if the excitation leads are the same.

All resistance ranges are digitally calibrated at the factory, with calibration factors stored in EEPROM on the signal conditioner board. This allows ranges and signal conditioner boards to be changed in the field without re calibrating the transmitter. If desired, the transmitter can easily be calibrated using external standards plus scale and offset in software.

High read rates at up to 60 or 50 conversions per second while integrating the signal over a full power cycle are ideal for high-throughput manufacturing processes. Peak and valley values are automatically captured and may be displayed via a front panel push-button command or a control signal at the rear connector, or be transmitted as serial data.

Custom curve linearization, available with the Extended version, makes this transmitter suitable for use with transducers whose output is a non-linear changing resistance. Linearization is provided by curvilinear spline fits, and the reading can be scaled in software for user-selected engineering units of measure.

Standard features of Micron MLT transmitters include:

• 4-20 mA, 0-10V or -10V to +10V analog transmitter output, isolated, jumper-selectable and user scalable. All selections provide 16-bit (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.
• Serial communications output, RS232 or RS485 (half or full duplex), jumper selectable. Three protocols are user selectable: Modbus RTU, Modbus ASCII, or Custom ASCII. Modbus operation is fully compliant with Modbus Over Serial Line Specification V1.0 (2002). The Custom ASCII protocol is simpler than the Modbus protocol and is recommended when all devices are Micron units.
• Dual solid state relays, isolated, for alarm or control. Rated 120 mA at 140 Vac or 180 Vdc.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12-32 Vac power is optional.

Easy Transmitter programming is via the 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. (P/N CBL04).