Description
Key Technical Specifications
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Model Number: VMIVME-4140
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Manufacturer: GE Fanuc / VMIC (General Electric)
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Channels: 16 isolated differential inputs (RTD 3/4-wire, TC J/K/T/E, ±10 V, 0-25 mA)
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Resolution: 16-bit (±0.015 % accuracy)
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Sampling Rate: 200 kS/s per channel continuous; burst 1 MS/s
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Isolation: 5 kVrms channel-to-bus; 500 V channel-to-channel
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Excitation: 2/5/10 mA RTD; 2.5 V TC cold-junction compensation
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Input Protection: ±30 V continuous, 60 V transient; MOV clamping
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Built-in-Test: Auto-zero & self-test; BIT LED & status register
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Communication: VME64x slave; DMA to dual-port RAM
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Operating Temperature: –55 °C…+125 °C (MIL-STD-810G)
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Form Factor: 6U single-slot VME64x
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MTBF: 450 000 h
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Status: Factory discontinued – new & tested spares available
GE VMIVME-7700RC
Field Application & Problem Solved
In combined-cycle plants the biggest headache is catching a 0.1 °C drift on a bearing RTD or a 0.05 mA shift on a governor servo without running external signal conditioners. The board solves that by living in the VME crate: it excites the RTD, cold-junction compensates the thermocouple, and dumps 16 samples into dual-port RAM every 5 µs. You’ll typically find one per EX2100 or test-cell rack where ±0.015 % accuracy on 690 V bus voltage and 4-20 mA servo pressure is required in the same scan. Core value: it collapses 16 isolated ADCs, anti-alias filters, surge clamps, and auto-zero logic into one card you can swap while the turbine is on turning gear
In combined-cycle plants the biggest headache is catching a 0.1 °C drift on a bearing RTD or a 0.05 mA shift on a governor servo without running external signal conditioners. The board solves that by living in the VME crate: it excites the RTD, cold-junction compensates the thermocouple, and dumps 16 samples into dual-port RAM every 5 µs. You’ll typically find one per EX2100 or test-cell rack where ±0.015 % accuracy on 690 V bus voltage and 4-20 mA servo pressure is required in the same scan. Core value: it collapses 16 isolated ADCs, anti-alias filters, surge clamps, and auto-zero logic into one card you can swap while the turbine is on turning gear
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Installation & Maintenance Pitfalls (Expert Tips)
RTD Excitation Must Match Sensor—Don’t Guess
Factory default is 2 mA. If you land a 1 mA thin-film RTD the self-heating drifts 0.3 °C. Use ToolboxST to set 0.5 mA for thin-film or you’ll chase phantom overtemperature trips
Factory default is 2 mA. If you land a 1 mA thin-film RTD the self-heating drifts 0.3 °C. Use ToolboxST to set 0.5 mA for thin-film or you’ll chase phantom overtemperature trips
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Burst Mode Heats the Card—Add Airflow Above 60 °C
At 1 MS/s the on-board regulators climb 15 °C. If your cabinet runs > 60 °C add a 24 VDC muffin fan or the thermal sensor throttles the ADC and you lose samples.
At 1 MS/s the on-board regulators climb 15 °C. If your cabinet runs > 60 °C add a 24 VDC muffin fan or the thermal sensor throttles the ADC and you lose samples.
P2 Connector Works Loose with Vibration
The 160-pin VME P2 connector is held by two screws; if you forget to tighten them the card creeps out and you lose half the channels on the next start-up. Torque screws to 0.4 Nm and tug-test the rear panel.
The 160-pin VME P2 connector is held by two screws; if you forget to tighten them the card creeps out and you lose half the channels on the next start-up. Torque screws to 0.4 Nm and tug-test the rear panel.
Spare Lead-Time Is 6-8 Weeks—Keep One on the Shelf
Factory stock is gone; new & tested spares are available but not overnight. If you crack a layer or burn the RJ-45 you’ll be down until the part arrives—keep one in stores or you’ll discover the weakness during the next grid event
Factory stock is gone; new & tested spares are available but not overnight. If you crack a layer or burn the RJ-45 you’ll be down until the part arrives—keep one in stores or you’ll discover the weakness during the next grid event
GE VMIVME-7700RC
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Technical Deep Dive & Overview
Internally the card is a 16-bit SAR ADC bolted to a 16-channel multiplexer and a dual-port FIFO. The FPGA handles autoscan timing; the VME master reads 16 samples in one 64-bit cycle. Lose the 5 V rail and the card goes dark, the FIFO empties, and the CPU throws “ADC TIMEOUT” within 50 ms. Swap takes two minutes: pull the old card, slide the new one in until the ejectors latch, and the crate sees all channels again—no software reload required
Internally the card is a 16-bit SAR ADC bolted to a 16-channel multiplexer and a dual-port FIFO. The FPGA handles autoscan timing; the VME master reads 16 samples in one 64-bit cycle. Lose the 5 V rail and the card goes dark, the FIFO empties, and the CPU throws “ADC TIMEOUT” within 50 ms. Swap takes two minutes: pull the old card, slide the new one in until the ejectors latch, and the crate sees all channels again—no software reload required
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