The Curtiss-Wright/VMETRO Vanguard PMC Top Spacer is a mechanical and electrical interface accessory that enables proper spacing, alignment, and signal routing for PMC (PCI Mezzanine Card) modules within PMC/PMC-X carrier boards. It manages PCI arbitration signals through jumper-selectable multiplexing, allowing either standalone PMC module operation or concurrent operation with the VG-PMC Exerciser. The spacer accommodates single-slot configurations and supports stacked PMC or PrPMC modules mounted on top of the VG-PMC carrier.
Technical Specifications
Power Requirements
• Requires both 3.3V and 5V power on the selected slot for operation
• Slot must provide 3.3V power supply
Signal Routing & Multiplexing
• Primary mux path: REQ#/GNT#/IDSEL from carrier board to Top Spacer PMC connector
• Secondary mux path: REQB#/GNTB#/IDSELB from carrier board to Top Spacer PMC connector
• Secondary signals always connected to Top Spacer PMC connector regardless of jumper position
• PMC P4 connector passed through to support modules with rear I/O
System Constraints
• Maximum two PCI devices per carrier board (one set or two sets of REQ#/GNT#/IDSEL available)
• VG-PMC Exerciser counts as one device
– Key Features
• Jumper-selectable signal multiplexing for flexible operational modes
• Primary position: Disables VG-PMC Exerciser; routes carrier REQ#/GNT#/IDSEL to mounted PMC module
• Secondary position: Enables VG-PMC Exerciser; routes carrier REQB#/GNTB#/IDSELB to mounted module
• Compatible with 32-bit or 64-bit slots supporting 3.3V or 5V signaling
• Supports cascaded PMC and PrPMC module configurations
– Compatibility & Integration
Installs in any PMC/PMC-X carrier board slot with appropriate power delivery. Integrates with the Vanguard family of bus analyzers and exercisers for PCI and PCI-X debugging, analysis, and compliance testing. Enables system configurations where direct PMC module slotting is impractical or where multiple modules must operate in controlled device hierarchies.
