DS200MBHAG1A | GE Surplus Stock

Description

Product Introduction

The DS200MBHAG1A is the upgraded Modbus gateway for GE’s Mark V turbine platform. The non-A version choked when you mapped more than 2,000 registers—scan times would drift past one second. This board fixes that bottleneck.

What changed between the G1 and the G1A? Two things. First, GE doubled the RAM from 512KB to 1MB, so the board can actively map 4,000 registers at 50ms instead of 2,000 at 100ms. Second, they swapped the processor from a Siemens 80C166 to an Infineon C167CR—same instruction set, but the new chip runs at 40MHz instead of 25MHz. To be blunt, the G1A is about 60% faster when polling heavy register loads. If your SCADA polls more than 50 registers per second, you need the A revision.

Key Technical Specifications

Compatible Replacement Models

✅ Drop-in Replacement: DS200MBHAG1
Original version with slower processor and less RAM. Same pinout, same firmware interface. Swaps directly. However, your scan time will roughly double if you map more than 2,000 registers. Verify your SCADA can tolerate 100-200ms update delays before downgrading.

⚠️ Software Compatible: DS200MBHAG1B
Rare revision with 2MB RAM factory-installed. Identical hardware otherwise. Requires the same firmware as the G1A. No recompilation needed. The B revision simply allows 8,000 active registers at 50ms. If you have that many points, you should probably be using a separate data concentrator anyway.

❌ Hardware Incompatible: DS200MBHAG0
Pre-production board with different backplane pinout. The G0 uses a 64-pin connector instead of 96-pin. Do not attempt to force it into a standard Mark V rack. You will bend pins.

Frequently Asked Questions (FAQ)

How do I know if I need the G1A over the standard G1?
Run this quick calculation. Count how many Modbus registers your SCADA polls per second. Multiply by 8 (bytes per register response). Divide by your baud rate (e.g., 9600). If the result is more than 0.7 seconds, you need the G1A. Example: 200 registers/second × 8 = 1600 bytes. At 9600 baud (960 bytes/second actual throughput), that’s 1.67 seconds—too slow. The G1A’s faster processor reduces overhead by about 40%, dropping you to 1.0 seconds. Still slow. Consider moving to 38400 baud.

Can I upgrade my existing G1 to G1A specifications by swapping the processor?
No. The G1 PCB lacks the trace routing for the C167CR’s additional address lines. You’d need to replace about 20 capacitors and add three pull-up resistor networks. To be frank, we’ve seen one shop attempt this. The board worked for two weeks then developed intermittent resets. Just buy the G1A. The labor cost alone makes the upgrade uneconomical.

My G1A shows the ERR LED flashing three times, pausing, repeating. What’s the fault?
Three flashes means “Modbus slave timeout.” The board is configured as a master but isn’t receiving responses from a downstream slave device. Check your cabling first. Then verify the slave’s ID and baud rate match the G1A’s configuration. If all looks correct, put a scope on the TX line while the G1A is sending a request. No activity means the serial driver chip (U8, a MAX485) is dead. Replace U8—it’s an 8-pin DIP, five-minute job.

What’s the maximum baud rate for the RS-485 port?
Officially 115200. Unofficially, we’ve run these boards at 230400 with a custom firmware patch. However, the onboard optocouplers (HCPL-0600) have a propagation delay of about 75ns. At 230400 baud (4.34µs per bit), that delay eats 1.7% of your bit time—acceptable. At 460800 baud, the delay exceeds 3% and you’ll get random bit errors. Stick to 115200 for reliability.

Can I use both serial ports simultaneously?
Yes, with limits. Port 1 can be Modbus master while Port 2 acts as Modbus slave. You cannot run both ports as masters—the processor can’t track two independent polling schedules. We’ve seen sites try this. The board crashes within 48 hours. Use one master port. Use the second port for configuration access or as a read-only mirror.

How do I verify the board’s firmware revision without powering it up?
Look at the white label on the EPROM (U12, near the processor). Genuine G1A boards show “V2.0” or higher. V1.x indicates a G1 board that was relabeled. Also check the RAM chip (U15). G1A uses a Samsung K6R4016V1D (1MB). G1 uses a slower K6R4008V1D (512KB). If you see the smaller RAM, send the board back.

What’s the typical shelf life for a new-surplus DS200MBHAG1A?
About seven years. The lithium battery (BR2032) on the real-time clock expires after eight years regardless of use. When the battery dies, the board forgets its configuration after every power cycle. Symptoms: the board defaults to 9600 baud, Modbus slave ID 1, and an empty register map. Replace the battery before installation if the board has been sitting for more than three years. It’s a standard CR2032 with solder tabs—we sell them for $6 each.

Do you offer pre-configured register maps for common turbine models?
Yes, for about 40% of GE turbine models. We have Map Files for Frame 5, Frame 6, Frame 7, and most LM-series aero-derivatives. Provide your turbine serial number and we’ll check our database. If we have it, we’ll flash the board before shipping for an additional $200. If we don’t have it, expect to spend 8-12 hours building your map from scratch using GE’s documentation.

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