Description
Key Technical Specifications
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Model Number: VMIVME-5504
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Manufacturer: GE (legacy VMIC), later Abaco Systems
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Function: Master/slave repeater link for VME64
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Propagation Delay: 400 ns @ 5 ft, +4 ns/ft
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Data Width: 32-bit DMA, D08/D16/D32, A16/A24/A32
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Distance: 1000 ft (copper) or 100 m (fiber multimode)
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Slaves Supported: Up to 16 slave chassis per master
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IRQ Pass-Thru: All VME IRQ 1-7 forwarded transparently
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Medium: Shielded twisted pair (5504L) or 62.5/125 µm multimode fiber (5504S)
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Connectors: RJ-45 (copper) or SC duplex (fiber); front-panel 96-pin DIN
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Power: +5 V @ 1 A per board typical
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Form Factor: 6U single-slot VME64 slave (each end)
GE VMIVME-7700RC
Field Application & Problem Solved
Coal-plant DCS racks live in separate rooms—radiation side vs. safe side. VME backplane can’t stretch 900 ft through conduit shared with 4 kV feeders, and copper picks up ground-loop noise. Drop a VMIVME-5504M (master) in the main rack and a 5504S (slave) in the remote panel; the fiber pair regenerates clean VME cycles with zero copper in the path. I’ve used this exact link to tie a turbine governor crate to a 300 ft-away feed-water heater I/O rack: no CRC errors, no retries, even when the 13.8 kV breaker slams shut and ground potential jumps 80 V. Core value: transparent bus extension that behaves like one long backplane—no software drivers, no address remapping, just plug-and-play distance with lightning immunity.
Coal-plant DCS racks live in separate rooms—radiation side vs. safe side. VME backplane can’t stretch 900 ft through conduit shared with 4 kV feeders, and copper picks up ground-loop noise. Drop a VMIVME-5504M (master) in the main rack and a 5504S (slave) in the remote panel; the fiber pair regenerates clean VME cycles with zero copper in the path. I’ve used this exact link to tie a turbine governor crate to a 300 ft-away feed-water heater I/O rack: no CRC errors, no retries, even when the 13.8 kV breaker slams shut and ground potential jumps 80 V. Core value: transparent bus extension that behaves like one long backplane—no software drivers, no address remapping, just plug-and-play distance with lightning immunity.
Installation & Maintenance Pitfalls (Expert Tips)
Master/slave order is jumper-fixed
Only the 5504M drives the line first; the 5504S is slave. If you flip the cards the link comes up but arbitration collapses under heavy DMA—random bus errors every few hours. Check P2 jumpers before you button up
Only the 5504M drives the line first; the 5504S is slave. If you flip the cards the link comes up but arbitration collapses under heavy DMA—random bus errors every few hours. Check P2 jumpers before you button up
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Fiber is multimode only
Single-mode patch cords give 6 dB mismatch and the receiver won’t lock. Use 62.5/125 µm SC-SC duplex; keep bend radius >30 mm or you’ll fracture the glass and lose link margin.
Single-mode patch cords give 6 dB mismatch and the receiver won’t lock. Use 62.5/125 µm SC-SC duplex; keep bend radius >30 mm or you’ll fracture the glass and lose link margin.
Termination is automatic—do not add resistors
The 5504 applies on-card electrical termination when it senses end-of-cable. Adding external 120 Ω resistors doubles the load and halves the signal swing—results in intermittent “AC FAIL” traps.
The 5504 applies on-card electrical termination when it senses end-of-cable. Adding external 120 Ω resistors doubles the load and halves the signal swing—results in intermittent “AC FAIL” traps.
IRQ pass-thru is wire-OR
All seven IRQ lines are forwarded; if the remote crate also generates IRQ7 you’ll get collisions. Mask or relocate IRQ sources in the secondary chassis so only one end asserts each level.
All seven IRQ lines are forwarded; if the remote crate also generates IRQ7 you’ll get collisions. Mask or relocate IRQ sources in the secondary chassis so only one end asserts each level.
Front-panel LEDs lie after a surge
Green “LINK” stays on even if only one pair is good. After lightning, swap the cable first—90 % of the time it’s shield damage, not a dead board
Green “LINK” stays on even if only one pair is good. After lightning, swap the cable first—90 % of the time it’s shield damage, not a dead board
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GE VMIVME-7700RC
Technical Deep Dive & Overview
The 5504 is a transparent physical-layer repeater: VME signals → differential line drivers → 1000 ft copper or 100 m fiber → differential receivers → VME signals. A 22V10 PLD handles bus time-out and retry; no firmware means nothing to corrupt. Because the link regenerates all VME signals—including IACK, DTACK, and RETRY—remote cards appear at identical addresses, so legacy drivers never know the bus is extended
The 5504 is a transparent physical-layer repeater: VME signals → differential line drivers → 1000 ft copper or 100 m fiber → differential receivers → VME signals. A 22V10 PLD handles bus time-out and retry; no firmware means nothing to corrupt. Because the link regenerates all VME signals—including IACK, DTACK, and RETRY—remote cards appear at identical addresses, so legacy drivers never know the bus is extended
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