TxIsoRail 4-20 mA Isolated Temperature Transmitter

Specifications

Sensor Input

User defined. The supported sensors are listed in Table 1, along with their maximum ranges.

• Thermocouples: Types J, K, R, S, T, N, E and B to IEC 60584 (ITS-90). Impedance >> 1 MΩ.
• Pt100: Excitation: 180 μA, 2 or 3-wire connection (for 2-wire sensors, tie terminals 2 and 3 together). α= 0.00385, according to IEC 60751 (ITS-90).
• Voltage: 0 to 50 mVdc, 0 to 10 Vdc. Impedance >> 1 MΩ. Note: 0-10 Vdc input type requires an internal jumper switching.
• Current: 0 to 20 mA, 4 to 20 mA. Impedance 15.0 Ω (+ 1.9 Vdc).

Output

2-wire 4-20 mA, linear with respect to the measured signal.

Resolution: 0.001 mA (14 bits).

Total Accuracy: Better than 0.3% of the maximum span for thermocouples and 0.2% for Pt100 and voltage.

Response Time: < 500 ms.

Isolation: Between the sensor and the 4-20 mA loop (1000 V / 1 min).

Power Supply: 12 to 35 Vdc, across the transmitter.

Maximum Load (RL): RL (max.)= (Vdc – 12) / 0.02 [Ω] (where Vdc = Power supply voltage).

Operating Temperature: -40 to 85 °C.

Humidity: 0 to 90% UR.

Electromagnetic Compatibility: EN 50081-2, EN 50082-2.

Internal protection against polarity inversion.

Cold junction compensation for thermocouples.

Certifications: CE, UKCA.

Configuration

If the transmitter is already configured as required by the application, it may be installed and used. For distinct configurations, use the TxConfig software and TxConfig Interface. The TxConfig interface connects the transmitter to a PC via USB, as shown in Figure 1. Software updates are available on the NOVUS AUTOMATION website.

Figure 1: TxConfig Interface USB connections. This diagram shows the transmitter connected via a USB interface cable to a PC. The transmitter has terminals for sensor input (1, 2, 3) and output/power (4, 5, 6).

Figure 3: TxConfig Interface USB connections - Loop powered. This diagram shows the transmitter connected to a PC via USB, powered by the current loop, with sensor and load connected.

Once connected, the TxConfig software displays configuration options. Access the Help menu for usage instructions. The main screen is shown in Figure 2.

Figure 2: TxConfig main screen. This image depicts the software interface with fields for Input Sensor selection (e.g., Thermocouple K, Pt100, 0-10V, 0-20mA), Measuring Range (Min/Max values), Line Noise Rejection (50/60 Hz), Sensor Failure action (Downscale/Upscale), Zero Correction, and Device Information. Buttons like 'Apply' and 'Read Device' are visible.

Key Configuration Fields:

• 1. Input Sensor: Select the desired temperature sensor from available options (see Table 1).
• 2. Measuring Range: Define the beginning and end of the range. A higher low scale limit than the full scale limit results in a decreasing current output (20~4 mA). Values must be within the sensor's measuring range and respect minimum span values.
• 3. Line Noise Rejection: Select the line frequency (50 Hz or 60 Hz) to filter induced noise for better performance.
• 4. Sensor Failure: Configure the transmitter's output behavior (upscale or down-scale) when a sensor failure occurs.
• 5. Zero Correction: Allows for small sensor adjustments.
• 6. Device Information: Displays relevant transmitter data for technical assistance.
• 7. Apply: Sends the new configuration to the transmitter.
• 8. Read Device: Retrieves the current transmitter parameters.

Factory Default Configuration: Pt100 input, 0 to 100 °C, 60 Hz filtering, and upscale (20 mA) output for sensor fail.

The transmitter requires power during configuration. External power is recommended, or it can be loop-powered as shown in Figure 3.

Electrical Connections

The transmitter connects to the sensor and power supply via terminals. Terminals 1, 2, and 3 are for sensor input. For 2-wire Pt100, terminals 2 and 3 should be connected together.

Figure 5: Transmitter wiring (Pt100). Shows a Pt100 sensor connected to terminals 1, 2, 3. Terminals 2 and 3 are jumpered. Power supply and load are connected to terminals 4 and 5.

Figure 6: Transmitter wiring (Thermocouple, mA, Vdc). Shows a thermocouple, mA, or Vdc sensor connected to terminals 1, 2, 3. Power supply and load are connected to terminals 4 and 5.

The LOAD represents the input shunt of an instrument measuring the 4-20 current loop.

Electrical Connections – 0-10 Vdc Input: For 0-10 Vdc input, an internal hardware change is required. Open the instrument case and change the jumper as shown in Figure 7.

Figure 7: Jumper position for 0-10 Vdc input. Shows a jumper block with positions 1-2 and 2-3. Position 1-2 is for 0-10 Vdc input, and position 2-3 is for all other input types.

Mechanical Installation

The transmitter is designed for DIN rail mounting. Its dimensions are presented in Figure 4.

Figure 4: Transmitter dimensions. Shows a diagram with the transmitter's external dimensions: 77 mm height, 69 mm width, 19 mm depth, with mounting brackets.

Operation

All input types and the 4-20 mA output are factory calibrated. Manual offset trim is available via the front ZERO key for fine adjustments. Press and hold the key for at least 2 seconds to adjust the output current.

Offset correction can also be performed using the TxConfig software's 'Zero Correction' field (Figure 2). The serial adapter can be connected while the transmitter is operating.

Users should select the sensor and configure the span that best suits the application, ensuring it does not exceed the transmitter's maximum supported range or fall below the minimum span.

Transmitter accuracy is related to the total sensor span, regardless of the configured output scale. For example, a Pt100 with a maximum input span of -200 to +650 °C (0.2% accuracy) has a maximum error of 1.2 °C (0.2% of 800 °C), whether the full span or a narrower span (e.g., 0 to 100 °C) is used.

Note: When using a Pt100 simulator, ensure its excitation current (0.18 mA) is compatible with the transmitter's specification.

Warranty

Warranty conditions are available on the NOVUS AUTOMATION website: www.novusautomation.com/warranty.