Cold Junction Calibration on E2-16ISOTC-D modules

Setting Up Thermocouple and Cold Junction Compensation on a Sixnet E2-16ISOTC-D or E3-16ISOTC-1 Module

To configure thermocouple inputs on the Sixnet EtherTRAK‑2 I/O Module‑16 Isolated (E2‑16ISOTC‑D) for ISO (International Standard) compliance, you need to enable Cold Junction Compensation (CJC) and ensure the module’s settings match ISO‑1217/ISO‑1219‑1 requirements for thermocouple measurement.

1. Understand Cold Junction Compensation

Thermocouples measure the voltage difference between the hot junction (measuring point) and the cold junction (reference point). To get the absolute hot junction temperature, the cold junction must be at a known, stable temperature (ideally 0 °C).

• CJC adjusts the measured voltage to account for the actual cold junction temperature, so no ice bath is needed TC+1.
• The E2‑16ISOTC‑D supports built‑in CJC using an internal temperature sensor (RTD/thermistor) to monitor the terminal block temperature 

2. Configure the E2‑16ISOTC‑D for ISO

The E2‑16ISOTC‑D supports thermocouples J, K, E, R, T, B, L, N, and S  For ISO compliance:

• Enable CJC in the module’s configuration software (e.g., Red Lion’s EtherTRAK‑2 software or equivalent).
• Select the thermocouple type from the supported list.
• Ensure the cold junction temperature source is set to the internal sensor (or an external sensor if using a separate CJC unit).
• Set the reference temperature to 0 °C (ice point) for ISO‑1217 compliance.
• Verify accuracy and resolution meet ISO requirements (typical uncalibrated accuracy ±0.5 °C for the E2‑16ISOTC‑D)

3. Wiring and Signal Conditioning

• Connect thermocouple wires to the correct channel terminals.
• Ensure proper insulation and shielding to avoid noise.
• If using an external CJC unit, connect its output to the module’s CJC input (if available) and configure the software to use that source.

4. Software Configuration Steps

1. Open the EtherTRAK‑2 configuration tool.
2. Select the E2‑16ISOTC‑D module.
3. In the channel settings, choose the thermocouple type.
4. Enable Cold Junction Compensation.
5. Set the cold junction temperature to 0 °C.
6. Save and download the configuration.
7. Power cycle the module to apply changes.

5. Verification

• Test with a known reference source (e.g., calibrated temperature bath) to verify CJC accuracy.
• Check that the module’s output matches ISO‑1217/ISO‑1219‑1 tables for the selected thermocouple type.
• Ensure the software logs and displays values in °C with correct CJC applied.

Tip: If your application requires higher precision than the built‑in CJC, consider using a temperature‑controlled enclosure or a dedicated CJC unit TC.

By following these steps, you can set up the SIX e2‑16 to ISO‑compliant thermocouple measurement with accurate cold junction compensation

 

E2‑16ISOTC‑D Wiring & Cold‑Junction Setup Guide

1 Identify Terminal Blocks & CJC Zones

The E2‑16ISOTC‑D has four terminal blocks, each with its own cold‑junction sensor.

• Block 1: Channels 1–4 → CJC Sensor #1 (AI:16 / Modbus 3:0017)
• Block 2: Channels 5–8 → CJC Sensor #2 (AI:17 / Modbus 3:0018)
• Block 3: Channels 9–12 → CJC Sensor #3 (AI:18 / Modbus 3:0019)
• Block 4: Channels 13–16 → CJC Sensor #4 (AI:19 / Modbus 3:0020)
• Each block has its own temperature reference for accurate thermocouple compensation.

2 Wire Thermocouples to Each Channel

Recommended

Each channel is fully isolated and accepts any supported thermocouple type (J, K, T, E, R, S, B, N).

• Connect TC+ → CHx+
• Connect TC– → CHx–
• Use thermocouple‑grade wire all the way to the module
• Keep polarity correct (Type K: Yellow = +, Red = –)
• Do not bond the thermocouple to earth at the module
• Shield → ground at one end only to avoid noise

3 Wire Raw mV Sensors (Optional Mode)

If the channel is configured for ±250 mV mode, wire the sensor directly to the differential input.

• Connect mV+ → CHx+
• Connect mV– → CHx–
• Use twisted‑pair shielded cable
• Keep leads short to reduce noise pickup

4 Configure Channels in SIXnet I/O Toolkit

Setup

Each channel must be set to Thermocouple or Raw mV mode in software.

• Open your station → right‑click E2‑16ISOTC‑D → Configure Module
• For each channel:
  • Select Thermocouple or Raw mV
  • Choose TC type (J/K/T/etc.) if applicable
  • Enable 50/60 Hz filtering if needed
• Download configuration to the station and reboot

5 Verify Cold‑Junction Compensation Readings

Important

CJC temperatures ensure accurate thermocouple readings by compensating terminal temperature.

• Read CJC values at:
  • AI:16 → CJC #1
  • AI:17 → CJC #2
  • AI:18 → CJC #3
  • AI:19 → CJC #4
• In Modbus: 3:0017 – 3:0020
• Confirm CJC values are reasonable (20–40°C typical indoors)

6 Validate Thermocouple or mV Readings

Once wiring and configuration are complete, verify live readings.

• Read channels AI:1–16 (Modbus 3:0001–3:0016)
• Compare with a handheld thermometer or mV source
• Ensure readings track correctly with temperature changes

Cold‑Junction Compensation Map (Quick Reference)

 

01 Create a new project and station

Start Here

You define the EtherTRAK‑2 module and basic comms before touching I/O settings.

Open Sixnet I/O Toolkit → File → New Project

• Give the project a name and choose a folder
• When the wizard appears, select Add a new station to the project
• In the station type dropdown, choose EtherTRAK2
• Enter a station name (e.g., E2-16ISOTC-D) and click OK

02 Set station number and IP address

This ensures the PC can talk to the module over Ethernet or USB without conflicts.

In the station configuration window → General Properties

• Set Station number (e.g., 2) so it’s unique on the network
• Confirm or set the IP address (default often 10.1.0.2 for station 2)
• Enter the module serial number if you want it documented
• Click OK to save general properties

03 Open module I/O configuration

Now you configure each of the 16 analog channels for thermocouple or mV.

Right‑click the station → Configure → Configure station/module…

• In the configuration window, locate the I/O or Analog Inputs section
• Select the E2-16ISOTC-D module from the list if multiple modules exist
• Open the Analog Input Channels dialog for the 16 TC/mV inputs

04 Configure each input channel (TC or mV)

Most Common Step

You tell the module what each channel is measuring and how to scale it.

• For Channel 1 (AI1):
  • Set Mode to Thermocouple or mV
  • If Thermocouple, choose type: J, K, E, R, T, B, C, N, S
  • If mV, select the ±250 mV range
  • Optionally set filtering (50/60 Hz) and any scaling/engineering units
• Repeat for Channels 2–16 as needed
• Keep unused channels disabled or left at default to reduce noise

05 Verify cold junction compensation handling

CJC is automatic, but you should know where the temperatures are read.

• Confirm that CJC is enabled (usually default in TC mode)
• Note that the four CJC temperatures are available at AI:16–19
  • Modbus registers 3:0017–3:0020 hold these values
• No extra programming is needed for CJC—the module uses them internally for TC readings

06 Save configuration and prepare to download

You commit your settings in the project before pushing them to the hardware.

In the configuration window → OK → then File → Save Project

• Click OK to close the station/module configuration
• Save the project so you can reload or modify later
• Make sure the PC is connected to the E2 (Ethernet or USB) and powered

07 Select communication device

You tell I/O Toolkit how it will reach the E2 module.

In I/O Toolkit → Device → Select…

• Choose Ethernet if you’re using the network port
  • Enter the E2’s IP address (e.g., 10.1.0.2)
• Or choose USB if you’re directly connected via USB
• Confirm the selection and close the dialog

08 Download configuration to the E2-16ISOTC-D

Applies Changes

This step actually programs the module with your settings.

In I/O Toolkit → Tools → Load Configuration (or similar load option)

• Select the station you just configured
• Start the Load/Download process
• Wait for the progress bar to complete without errors
• If prompted, allow the module to reboot

09 Test live readings and CJC values

You confirm that thermocouple/mV inputs and CJC channels are behaving correctly.

In I/O Toolkit → Online → Monitor I/O (or similar monitor view)

• View AI1–AI16 and verify temperatures or mV values change with the process
• Check AI:16–19 for CJC temperatures (each block of 4 channels has one CJC)
• Compare readings with a handheld meter or known temperature source
• If values look off, revisit channel type, wiring polarity, and filtering settings

10 Optional: Set up Modbus mapping and documentation

You make it easy for PLC/SCADA to read the values later.

• Document the mapping: AI1–AI16 → Modbus 3:0001–3:0016
• Document CJC: AI:16–19 → Modbus 3:0017–3:0020
• Add comments in the project for each channel (e.g., TC K – Reactor Inlet)
• Save and back up the project file for future maintenance