B&R X20AT6402 Thermocouple Input Module

X20: X20 I/O system series

AT: Analog Temperature input

6402: 6channel thermocouple module; X20cAT6402 is the conformalcoated version (condensation & corrosivegas resistant)

General Description

X20AT6402 is a 6channel thermocouple temperature acquisition module for X20 PLC distributed I/O. It features integrated terminal coldjunction compensation, supporting J/K/N/S/B/R thermocouple types. SigmaDelta 16bit ADC; it can output engineering temperature values or raw millivolt readings.

⚠️Note: No galvanic isolation between channels; isolation exists between bus side and I/O side.

Mandatory accessories: X20TB12 (12pin terminal block), X20BM11 bus base. Terminals are NOT supplied with the module.

Key Technical Specifications

Wiring Notes

1. Each thermocouple channel uses 2 terminals (TC+, TC). Six channels occupy 12 pins, matching X20TB12 terminal block.
2. Do not reverse thermocouple polarity; always use matched thermocouple extension wires.
3. No galvanic isolation between channels. For multipoint measurement, control reference potential difference to avoid commonmode interference.
4. Coldjunction compensation uses onboard terminal temperature measurement; keep terminal block away from heatgenerating components.

Software Configuration (Automation Studio)

1. Add hardware `X20AT6402` in hardware tree.
2. Independently set sensor type (J/K/N/S/B/R) for each channel.
3. Configure filter time; select output: engineering temperature ℃ or raw millivolt value.
4. Enable wirebreak diagnosis.

Alternative X20Series Selection

Typical Application

Heattreatment furnaces, ovens, injection molding machines, extruders, kilns, multipoint temperature acquisition for energyrelated equipment.

Secondhand Module Inspection Checklist

1. Visual check: No terminal burn marks; backplane gold contacts intact.
2. Poweron test: RUN LED normal; no module fault alarms.
3. Functional test: Connect known Ktype thermocouple; compare readings against reference thermometer across all channels.
4. Verify hardware revision; distinguish standard version vs conformalcoated `c` variant.

B&R X20AT6402 Installation Manual (Practical English Version)

Official full document: X20 System User´s Manual, chapter 9.32.7 for X20AT6402. Download from B&R official website after login. X20cAT6402 shares identical hardware mechanics with conformal coating applied.

This is slicestyle X20 I/O. Mandatory parts: X20BM11 bus base + X20TB12 spring terminal block; terminals are not included with module.

1 Safety Preconditions

1. Install only inside electrical cabinet; protection rating IP20. Not for outdoor deployment.
2. Disconnect 24 V DC power for installation / removal / wiring. Hotswap is supported, but perform wiring with power removed.
3. ESD protection: Wear antistatic wrist strap. Do not touch goldplated backplane contacts directly by hand.
4. Environmental conditions

2 Mechanical Installation (DINrail TS35 EN60715)

2.1 Mandatory Clearance for Heat Dissipation

Minimum 10 mm clearance left and right of each module.

Horizontal mounting: ≥35 mm free ventilation space above and below module.

Vertical mounting: CPU must be placed below all I/O modules.

Tilt angle must not exceed 120°.

2.2 Assembly Procedure

1. Clip X20BM11 bus base onto DINrail, press down to lock firmly.
2. Snap X20 sliceI/O modules sequentially onto base, keep modules tightly adjacent.
3. Insert X20AT6402 downwards into X20BM11 base until audible click; confirm both side latches fully engaged.
4. Fit X20TB12 (12pin spring terminal block) onto front face of module. Terminals can be detached for offline prewiring.

Removal Procedure

1. Remove power supply.
2. Press triangular release latch on top of module; lift module upward to separate from bus base.
3. Pull terminal block straight outward.

2.3 Mandatory Hardware BillofMaterials

3 Electrical Wiring

3.1 Bus Power Supply

X20BM11 receives 24 VDC to supply backplane bus and X20AT6402 module.

Power consumption: Bus side 0.01 W; I/O side 0.91 W.

3.2 Thermocouple Field Wiring (X20TB12 terminals)

Six thermocouple channels, each channel uses TCx+, TCx differential pair; total 12 pins.

Always use matched thermocouple extension wire; strictly observe polarity.

⚠️Critical: No interchannel isolation; bustoI/O isolation present. Keep commonmode voltage ≤±15 V to prevent measurement drift for multisensor systems.

Coldjunction compensation: Onboard terminal temperature measurement. Locate terminal block away from contactors, power supplies and other heatgenerating devices.

Cabling practice: Run thermocouple lowlevel mV signal cables separately from power cables; avoid parallel bundling. Shield cable singleend grounding: connect shield to cabinet ground; leave sensorside shield floating.

Spring terminal wiring: Conductor crosssection 0.081.5 mm². Press spring tab with flatblade screwdriver, insert wire, release to lock conductor.

Recommended practice: Tie thermocouple negative terminals to module reference ground to suppress rippleinduced measurement error.

3.3 Terminal Assignment

4 LED Status Indicators

Module frontpanel LED definition:

1. RUN Green: Steadyon = module healthy running; blinking = no valid configuration; off = no power / hardware fault.
2. ERR Red: On = module fault; blinking = channel wirebreak / sensor failure.

Wirebreak detection: Diagnostics enabled in software; ERR LED blinks on thermocouple opencircuit, PLC receives fault code.

5 Automation Studio Hardware Configuration

1. Insert hardware `X20AT6402` in hardware tree; verify firmware compatibility.
2. Perchannel parameters:

Sensor type: J / K / N / S / B / R

Filter time:1 ms ~ 66.7 ms; set to 66.7 ms for 50 Hz mains noise suppression.

Output mode: Engineering temperature ℃ / raw mV value.

Resolution:0.1℃ /0.01℃ selectable.

Enable wirebreak diagnosis.

3. Download hardware configuration, restart X20 I/O bus.
4. Validation: Connect known thermocouple; crosscheck temperature readings against reference thermometer.

6 Commissioning & Troubleshooting

7 Maintenance & Sparepart Replacement

1. Hotswap capability: Poweroff swap is preferred; live module replacement allowed. No project redownload required when replacing with identical part number.
2. Cabinet environment: Keep cabinet dustfree, avoid condensation.
3. Distinguish standard X20AT6402 vs coated X20cAT6402; spareparts cannot be interchanged arbitrarily.

8 Official Document Access

1. B&R official website → Support → Document download, search partnumber `X20AT6402`;
2. Available documents: Datasheet, X20 System User Manual. B&R user login required for PDF download.

X20AT6402 Faultcode Reference & ST Variable Mapping Example

1 Channel Diagnostic Status (2 status bits per channel)

Each thermocouple channel returns: Temperature value + channel status bits

Global module fault flag: `0x8000` = general module failure

LED Diagnostic Table

2 ST StructuredText Variable Mapping (Automation Studio)

X20AT6402 has 6 channels. Each channel delivers INT temperature value + channel status byte.

Two resolution modes available: 0.1 ℃ (INT), 0.01 ℃ (DINT).

3 Comprehensive Field Troubleshooting List

1. All channels read 32767

Symptom: All channels return `0x7FFF`, channelstatus =3 (opencircuit).

Checklist: X20TB12 fully seated; X20BM11 latches locked; 24 V supply voltage drop.

2. Singlechannel returns 32767, other channels normal

Possible rootcauses: Broken thermocouple / extension wire; loose terminal crimp; reversed thermocouple polarity.

3. Temperature reading jitter / drift

1) Filter time too short and mains interference present; set filter time to 66.7 ms for 50 Hz suppression.

2) Thermocouple extension wire runs parallel with power cables; separate cable routing; singleend shield grounding at cabinet.

3) Interchannel commonmode voltage >±15 V. No interchannel isolation; large referencepotential difference between multiple thermocouples.

4. ERR LED solid red, RUN LED blinking green

Firmware version mismatch; hardware configuration mismatches physical hardware. Distinguish X20AT6402 vs X20cAT6402, do not crosscompile configuration.

5. Fixed 273 ℃ reading

Typical opencircuit symptom when wirebreak diagnosis is enabled; inspect sensor wiring loop first.

4 Diagnostic Function Block Tip

Automation Studio standard library provides `X20DiagGetChannelState()` function block. It directly reads channel fault status without manual bitmask parsing.

Input hardwareID for X20AT6402: `161BA9`; function returns enumerated channelfault state.