Description
GE VMIVME-7700RC
Key Technical Specifications
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Model Number: VMIVME-5530M
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Manufacturer: GE (legacy VMIC)
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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: Up to 100 m shielded twisted pair between cards
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IRQ Pass-Thru: All VME IRQ 1-7 forwarded transparently
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Master Select: Jumper on P2 designates one board as link master
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Connectors: Dual 96-pin DIN 41612 front; RJ-45 or 9-pin D-sub for link
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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)
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MTBF: >300 kh @ 40 °C (MIL-HDBK-217F)
Field Application & Problem Solved
Power-plant DCS racks live in separate rooms—radiation side vs. safe side. VME backplane can’t stretch 90 ft through conduit shared with 4 kV feeders, so engineers drop a VMIVME-5530M pair in each chassis. The master board lives in the main rack; the slave sits in the remote panel. Together they regenerate clean VME cycles, pass all seven IRQ lines, and keep propagation under 1 µs—well inside the 2 ms scan budget.
Power-plant DCS racks live in separate rooms—radiation side vs. safe side. VME backplane can’t stretch 90 ft through conduit shared with 4 kV feeders, so engineers drop a VMIVME-5530M pair in each chassis. The master board lives in the main rack; the slave sits in the remote panel. Together they regenerate clean VME cycles, pass all seven IRQ lines, and keep propagation under 1 µs—well inside the 2 ms scan budget.
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.
Installation & Maintenance Pitfalls (Expert Tips)
GE VMIVME-7700RC
Master/slave order is jumper-fixed
P2 pin-21 strap designates master; only one board may be master. If both straps are on, the link comes up but arbitration collapses under heavy DMA—random bus errors every few hours. Check jumpers before you button up.
P2 pin-21 strap designates master; only one board may be master. If both straps are on, the link comes up but arbitration collapses under heavy DMA—random bus errors every few hours. Check jumpers before you button up.
Link cable is not CAT-5e*
Use individually shielded twisted pairs (Belden 9892 or equal). Standard CAT-5 lacks shield; after 50 ft you’ll see reflections on D08 cycles and the remote rack drops off the bus.
Use individually shielded twisted pairs (Belden 9892 or equal). Standard CAT-5 lacks shield; after 50 ft you’ll see reflections on D08 cycles and the remote rack drops off the bus.
Termination is automatic—do not add resistors
The 5530M applies on-card 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 5530M applies on-card 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, cycle power and watch for red “FAULT”; if it flashes, 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, cycle power and watch for red “FAULT”; if it flashes, swap the cable first—90 % of the time it’s shield damage, not a dead board.
Technical Deep Dive & Overview
The 5530M is a transparent physical-layer repeater: VME signals → differential line drivers → 100 m cable → 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 5530M is a transparent physical-layer repeater: VME signals → differential line drivers → 100 m cable → 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.
