D1400M Modbus Modules with RTD Input


The D1400M modules measure RTD (Resistance Temperature Detector) sensors. RTD sensors are resistors that have a very predictable change in resistance vs temperature. They are available in 2-wire, 3-wire and 4-wire versions. The D1400M contains four sensor input terminals and will accept any of the three different wiring methods. One of the four terminals is an excitation current output signal for the sensor.

The excitation current signal is passed through the sensor to generate a voltage. An isolated 15-bit analog to digital converter is used to measure the voltage across the sensor. The digital data values are scaled into 16-bit unsigned integer data format that represent a percentage of the full-scale input range. The data values are transmitted to a host computer using the Modbus RTU serial protocol via an RS-232 or RS-485 serial port.

The D1400M RTD input modules contain one open-collector digital output that can be used to control solid-state relays and annunciators. They can be pulled up to +30Vdc and sink up to 30mA without damage.

Because the Modbus protocol does not support Echoing the RS-232 versions of D1000M series are limited to one module per serial port. Applications requiring more than one module should use RS-485.

Use the links below to download a Datasheet, User’s Manual or view the Modbus Scaling Example.

Download Datasheet

Download Manual

Modbus Scaling Overview

The D1400M series modules can also be mounted on a DIN-Rail using the MK-1 mounting kit.

Measurement Ranges:
0.00385: -200 to +850C
0.00388: -100 to +125C
0.00392: -200 to +600C

Additional Information

Dimensions 3.6 × 2.45 × 1.1 in

• RTD Types: 0.00385, 0.00388, 0.00392
• Accuracy: +/-0.3 deg C.
• Resolution: 0.1 degree.
• Common mode rejection: 100db at 50/60 Hz.
• Input connections: 2, 3, or 4 wire.
• Excitation current: 0.25mA.
• Max lead resistance: 50 ohms.
• Input protection to 120Vac.
• Automatic linearization and lead compensation.
• One open collector digital output.

Click outside to hide the comparison bar