DS200TCCAG2A | GE Mark VI I/O Board

Description

Product Introduction (Anti-Template)

When you need more than 8 analog inputs in a single Mark VI slot, the DS200TCCAG2A is your only option. This board packs 16 channels into the same 6U footprint—double the capacity of the TCCAG1 series. The trade-off? Resolution drops to 14-bit (versus 16-bit), and the inputs share a common return instead of being fully isolated per channel.

The ‘2’ in the part number tells you this is the high-density variant in the TCCAG family. It’s built for applications where channel count matters more than ultra-high precision—monitoring multiple bearing temperatures, pressure transmitters on large turbine skids, or general-purpose analog signals in systems with many points. Compared to the TCCAG1A (8 channels, 16-bit, isolated), the TCCAG2A gives you twice the channels at 14-bit resolution with a shared return—a design that saves cost and board space but requires careful wiring to avoid ground loops. If you have 12-16 analog signals that don’t need the highest precision and you’re running out of rack slots, this board is a solution.

Key Technical Specifications

Compatible Replacement Models

Replacement options depend on your channel count and isolation requirements.

✅ Drop-in Replacement: The DS200TCCAG2 (no ‘A’ suffix) is a direct drop-in—same pinout, same 16 channels, same 14-bit resolution. The ‘A’ revision improved the accuracy from ±0.2% to ±0.15% and added a better temperature reference. If you find the base model, it works—just with slightly wider tolerances.

⚠️ Software Compatible: The DS200TCCAG1A (8 channels, 16-bit, isolated) fits the rack and uses the same communication protocol, but it’s not a drop-in replacement. If you swap a TCCAG2A for a TCCAG1A, you’ll lose channels 9-16 (they’ll read zero or invalid). You would need to re-wire your termination panel to use the TCCAG1A’s 8 channels. This is a downgrade, not an upgrade.

⚠️ Software Compatible: The DS200TCCAG1B (8 channels, 16-bit, isolated, filtering) is a high-precision alternative—but you lose half your channels. Only use if your channel count drops below 9.

❌ Hardware Incompatible: The DS200TCCBG1A (thermocouple board) and any discrete I/O boards use different pinouts—not suitable for analog inputs.

Frequently Asked Questions (FAQ)

What’s the difference between the TCCAG2A and the TCCAG1A?

The TCCAG1A is a precision board: 8 channels, 16-bit resolution, per-channel isolation, ±0.1% accuracy. The TCCAG2A is a high-density board: 16 channels, 14-bit resolution, shared return, ±0.15% accuracy. The trade-off is clear: channel count vs. precision and isolation. The TCCAG2A is for applications with many analog points that don’t require the highest accuracy—general monitoring vs. critical control loops.

Why doesn’t this board have per-channel isolation?

Board space. Sixteen channels with per-channel isolation would require 16 separate isolation transformers, which wouldn’t fit in a 6U VME board. The TCCAG2A uses a single isolation barrier between the entire analog input bank and the backplane—meaning all 16 channels share the same return. This is a cost and space-saving design. It’s acceptable for many applications, but it means you must be careful with ground loops: all signal commons must be at the same potential, or you’ll get measurement errors.

How do I wire this board to avoid ground loops?

Because the TCCAG2A has a common return, you must use a single-point grounding scheme. All signal sources (pressure transmitters, thermocouple transmitters, etc.) should have their commons tied together at the termination panel, and that common should be connected to the board’s return terminal. Do not ground the signal commons at multiple points—this creates ground loops that inject noise and offset errors. In practice, this means you should use isolated transmitters or isolate the signal commons with a single jumper. The TCCAG2A is less forgiving than the TCCAG1A in this regard—it rewards careful wiring.

Can I use this board with a Mark VIe controller?

No—the TCCAG2A uses the older Mark VI backplane pinout. Mark VIe uses a different assignment and typically uses the IS200TCCAG2A for high-density analog inputs. Use the Mark VIe-specific board for new installations.

How do I test this board before installation?

Testing the TCCAG2A requires checking all 16 channels and verifying common-return performance:

1. Visual inspection: Check for burnt or discolored components. The high-density board has more components in the same space—look for cracked solder joints, especially around the multiplexer.
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 2.0 or later.
4. Input test – voltage: Apply a precision 5.00V DC to channel 1. The read value should be 5.00V ± 0.0075V (0.15% of full scale). Repeat for channels 1-16.
5. Input test – current: Apply 12.00mA to a channel configured for 4-20mA. The read value should be 12.00mA ± 0.018mA.
6. Common-return test: Apply a 5.00V signal to channel 1 and a 0V signal to channel 2. The channel 2 read value should be within ±0.05% of full scale (not affected by the channel 1 signal). If it’s higher, the common return has a ground issue.
7. Channel crosstalk: Apply a full-scale signal to channel 1 and read channel 2. The crosstalk should be less than 0.1% of full scale (60dB CMRR).
8. Insulation: Measure the resistance between the input terminals (tied together) and the backplane. Should be >10MΩ.

What’s the most common failure on this board?

Two issues specific to the high-density design:

1. Multiplexer failure. The TCCAG2A uses a multiplexer to switch between channels—only one channel is digitized at a time. If the multiplexer fails, you’ll get stable readings on some channels and erratic readings on others. The symptom is “jumping” values on a specific channel while others are stable. The multiplexer is a surface-mount IC—not field-replaceable.
2. Common-return noise. Because the board has a common return, noise on the return path affects all channels equally. If you see the same offset on all channels (e.g., all channels read 0.2% high), the common return is picking up noise. This is usually a wiring issue, but in some cases, the board’s return trace can be damaged by high currents (if you accidentally short a channel to ground). The symptom is a consistent offset on all channels.

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

For SIL-2 applications (the TCCAG2A is typically not used in SIL-3 due to the shared return), we recommend:

• Visual inspection: Every 6 months
• Power-up test: Every 12 months
• Input accuracy check: Every 12 months (verify each channel reads within 0.15% of a precision source)
• Common-return test: Every 12 months (verify no significant crosstalk between channels)
• Full calibration: Every 5 years

What’s the lead time for a replacement TCCAG2A?

These boards are moderately available:

• New surplus: 2-4 weeks. The high-density board is less common than the TCCAG1A but still available.
• Refurbished: 1-2 weeks. Ensure the refurbisher tests all 16 channels—some only test a subset.
• Used/as-is: Available, but the multiplexer is a wear item—used boards may have intermittent channel failures.

Is there a direct Mark VIe equivalent?

Yes—the IS200TCCAG2A (Mark VIe version). The backplane pinout is different, and the Mark VIe board may have a different resolution (some variants use 16-bit). If you’re migrating to Mark VIe, plan to replace all high-density analog boards as part of the rack conversion.

What’s the update rate for all 16 channels?

The TCCAG2A scans channels sequentially with a 10ms total update time—each channel updates every 10ms, but they’re not sampled simultaneously. Channel 1 updates at t=0ms, channel 2 at t=0.625ms, etc. If you need simultaneous sampling (e.g., for differential measurements), you need a different board. The sequential sampling is acceptable for most monitoring applications but not for high-speed control.

What’s the correct input impedance for current mode?

In current mode (4-20mA), the TCCAG2A uses a 250Ω resistor—same as the TCCAG1 series. The 250Ω resistor is a common value for 4-20mA loops, providing 1-5V at the ADC. The shared return means all current loops must return to the same common point.

Can I mix TCCAG2A boards with TCCAG1A boards in the same system?

Yes—electrically and software-wise, they’re compatible. The TCCAG2A has a different channel count and resolution, but the backplane communication protocol is the same. Your control software (ToolboxST) will recognize each board type and map the channels accordingly. You can have a TCCAG2A for general monitoring and a TCCAG1A for critical channels (e.g., fuel control) in the same rack.

What’s the temperature drift on this board?

The TCCAG2A has a temperature drift of ±100ppm/°C—about 4x higher than the TCCAG1A’s ±25ppm/°C. This means the board’s accuracy changes by about 0.01% per 1°C change. If your control room swings 20°C, the board’s accuracy could shift by 0.2%—which is noticeable. For high-precision applications, the TCCAG2A is not ideal. For general monitoring, it’s acceptable.

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