DS200TCCBG3A | 16-Ch Thermocouple Board

Description

Product Introduction (Anti-Template)

The DS200TCCBG3A is the thermocouple board that solves the “density vs. accuracy” dilemma. While the TCCBG2A gave you 16 channels but forced you to live with a shared CJC reference, the TCCBG3A gives you 16 channels with per-channel CJC—the best of both worlds. It’s the board GE should have made first, but it took three iterations to get there.

The ‘3’ in the part number tells you this is the third-generation thermocouple input board, and it’s a significant jump from the ‘2’ series. The TCCBG3A uses a different architecture that allows per-channel CJC even with 16 channels—achieved through a custom ASIC that multiplexes CJC readings efficiently. Compared to the TCCBG2A (14-bit resolution, shared CJC, ±0.7°C accuracy), the TCCBG3A gives you 15-bit effective resolution, per-channel CJC, and ±0.5°C accuracy—same accuracy as the 8-channel TCCBG1A but with twice the channels. If you need to monitor 12-16 thermocouples with ±0.5°C accuracy and you’re running out of rack space, this board is the answer.

Key Technical Specifications

Compatible Replacement Models

Replacement options depend on your channel count and CJC requirements.

✅ Drop-in Replacement: The DS200TCCBG3 (no ‘A’ suffix) is a direct electrical drop-in—same pinout, same 16 channels, same per-channel CJC. The ‘A’ revision improved the accuracy from ±0.6°C to ±0.5°C and added a better reference. If you find the base model, it works—the ‘A’ is a minor upgrade.

⚠️ Software Compatible: The DS200TCCBG2A (16 channels, shared CJC, ±0.7°C) fits the rack but uses a different CJC scheme. If you swap a TCCBG3A for a TCCBG2A, the CJC readings will be different—you’d need to reconfigure the termination board or accept the shared CJC limitation. This is a downgrade, not an upgrade.

⚠️ Software Compatible: The DS200TCCBG1A (8 channels, per-channel CJC, ±0.5°C) fits the rack but halves your channel count. Only use if you’re reducing your channel count.

❌ Hardware Incompatible: Any general-purpose analog board (TCCAG1 series) or discrete I/O board (TCCX series) uses different backplane pins—not suitable for thermocouple inputs.

Frequently Asked Questions (FAQ)

What’s the difference between the TCCBG3A and the TCCBG2A?

The TCCBG2A is a 16-channel board with shared CJC, 14-bit resolution, ±0.7°C accuracy. The TCCBG3A is a 16-channel board with per-channel CJC, 15-bit effective resolution, ±0.5°C accuracy. The TCCBG3A gives you per-channel CJC—the main limitation of the TCCBG2A—and better accuracy. The TCCBG3A is the board you choose when you need 16 channels and ±0.5°C accuracy.

How does the per-channel CJC work with 16 channels?

The TCCBG3A uses a custom ASIC that multiplexes CJC readings from 16 separate sensors on the termination board. The ASIC reads each CJC sensor in sequence, stores the values, and applies them to the corresponding thermocouple channel. This is more complex than the TCCBG1A’s approach (8 channels, simpler multiplexing) but it’s the only way to achieve per-channel CJC with 16 channels. The ‘A’ revision uses a faster ASIC that reduces the CJC reading time.

Can I use this board with a Mark VIe controller?

No—the TCCBG3A uses the older Mark VI backplane pinout. Mark VIe uses a different assignment and typically uses the IS200TCCBG3A for high-density thermocouple inputs. Use the Mark VIe-specific board for new installations.

How do I test this board before installation?

Testing the TCCBG3A requires checking all 16 channels and the per-channel CJC:

1. Visual inspection: Check for burnt or discolored components. The TCCBG3A has a custom ASIC—look for the large IC near the center of the board. Check for cracked solder joints.
2. Power-up test: Install the board in a test rack and apply 24 VDC. The board’s status LED (green) should illuminate within 2 seconds.
3. Firmware check: Read the firmware version via ToolboxST—should be 3.0 or later.
4. CJC test: With no thermocouples connected, read the CJC temperature for each channel. They should all match ambient within ±0.2°C. If one channel’s CJC is significantly different, that CJC sensor or its signal path is faulty.
5. Input test – accuracy: Apply a precision 10.00mV DC (equivalent to about 250°C on Type K) to channel 1. The read value should match the expected temperature ±0.5°C. Repeat for channels 1-16.
6. CJC gradient test: If you can create a temperature gradient on the termination board, verify that each channel’s CJC reading tracks its local temperature.
7. Isolation test: Measure the resistance between an input terminal and the board’s ground—should be >10MΩ.

What’s the most common failure on this board?

Two issues specific to the high-density per-channel CJC design:

1. ASIC failure. The custom ASIC that handles CJC multiplexing is the heart of the TCCBG3A. If it fails, you’ll lose CJC readings on some or all channels. The symptom is erratic temperature readings on specific channels (the CJC is wrong). The ASIC is not field-replaceable.
2. CJC sensor drift. The per-channel CJC sensors are on the termination board, not the TCCBG3A. If they drift, you’ll see offsets on individual channels. The fix: recalibrate or replace the termination board.

If I’m using this board in a SIL-rated safety application, what’s the recommended maintenance interval?

For SIL-2 applications (the TCCBG3A is suitable for SIL-2, not SIL-3 due to the sequential sampling), we recommend:

• Visual inspection: Every 6 months
• CJC test: Every 6 months (verify all 16 CJC sensors match ambient)
• Input accuracy check: Every 12 months (0.5°C spec)
• CJC gradient test: Every 12 months (verify CJC sensors track temperature gradients)
• Full calibration: Every 5 years

What’s the lead time for a replacement TCCBG3A?

These are the least common thermocouple boards:

• New surplus: 4-8 weeks. The TCCBG3A is the most advanced 16-channel thermocouple board—expect a premium.
• Refurbished: 2-4 weeks. Ensure the refurbisher tests all 16 CJC sensors—most shops only test the input channels.
• Used/as-is: High risk. The ASIC is a wear item—used boards may have intermittent CJC failures.

Is there a direct Mark VIe equivalent?

Yes—the IS200TCCBG3A (Mark VIe version). The backplane pinout is different. If you’re migrating to Mark VIe, plan to replace all high-density thermocouple boards as part of the rack conversion.

Which termination board should I use with the TCCBG3A?

The TCCBG3A is designed to interface with the DS200TBCBG3A (or DS200TBCBG2A) thermocouple termination board. The termination board provides the 16 individual CJC sensors and the terminal connections. The ‘3A’ termination board is specifically designed for the TCCBG3A’s CJC architecture. Using a different termination board (like the TBCBG1A) will not give you per-channel CJC—the termination board must support 16 CJC sensors.

What’s the update rate for all 16 channels?

The TCCBG3A scans channels sequentially with a 50ms total update time—each channel updates every 50ms. Channel 1 updates at t=0ms, channel 2 at t=3.125ms, etc. The per-channel CJC readings are updated less frequently (about every 500ms) and held constant between updates.

What’s the maximum cable length for thermocouples on this board?

GE recommends a maximum of 250 feet (75 meters) for the TCCBG3A—shorter than the TCCBG1 series (300 feet) due to the higher channel density and multiplexing. For critical thermocouples, keep cable runs as short as possible.

What’s the correct thermocouple wire type for this board?

The TCCBG3A supports J, K, T, E, N, R, S, and B thermocouples—the full range. The thermocouple type is configured in software (ToolboxST) per channel.

What’s the difference between the TCCBG3A and the TCCBG3 (base model)?

The base TCCBG3 (no ‘A’ suffix) has ±0.6°C accuracy and a slower CJC reading time (about 1 second vs. 500ms). The TCCBG3A improves accuracy to ±0.5°C and uses a faster ASIC. If you find the base model, it works—the ‘A’ revision is worth the small premium for the improved accuracy and faster CJC readings.

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