Description
Hard Numbers: Technical Specifications
- Processor: Intel Pentium M, 1.8 GHz
- Memory: 512 MB SDRAM (Onboard, soldered)
- Bus Interface: VMEbus (A32/D32, Master/Slave, SysCon capable)
- Ethernet: 10/100Base-TX RJ-45 Port
- Storage: IDE Flash Disk Interface, Floppy Header
- Serial Ports: 2x RS-232 (DB-9)
- PMC Slots: 2x 64-bit PMC Sites (For dual I/O expansion)
- Watchdog Timer: Yes, Programmable
- Operating Temp: 0°C to +55°C
- Power Draw: +5V @ ~5.2A, +12V @ ~1.2A
VMIVME-7740-840
The Real-World Problem It Solves
Running large Mark VIe ToolboxST applications on older 256MB boards causes memory starvation and sluggish response times. This board provides the necessary RAM headroom to prevent system hangs during turbine startup. It eliminates the need for external PCs in the control cabinet, surviving the heat and vibration of a gas turbine enclosure.
Where you’ll typically find it:
- In Mark VIe turbine control cabinets as the primary UCSB host controller.
- Inside power generation control rooms, hosting the primary control application and data historian.
- In defense applications requiring dual PMC sites for expanded I/O density.
It prevents the dreaded “Out of Memory” kernel panic during critical control sequences.
Hardware Architecture & Under-the-Hood Logic
This is a full-blown PC integrated onto a 6U VME card. It serves as the VMEbus System Controller, bridging the PCI bus to the VME backplane. The Pentium M processor is chosen for its low power consumption and high performance in industrial settings.
- System Initialization: The BIOS initializes the 512MB SDRAM and probes the IDE flash disk for the control application.
- Bus Arbitration: The onboard VMEbridge ASIC manages the VMEbus protocol, allowing the CPU to read/write to other VME modules as memory-mapped I/O.
- I/O Expansion: The dual PMC sites allow for two independent I/O modules (like serial or fiber cards) without consuming additional VME slots, maximizing backplane real estate.
Field Service Pitfalls: What Rookies Get Wrong
Insufficient Power Budgeting
Rookies swap a 256MB board for this 512MB version without checking the power budget. The crate’s power supply can’t handle the extra 0.5A on the +5V rail, causing system-wide brownouts.
- Field Rule: Check the VME crate’s total power budget. The draws significantly more current than older 68040 boards. Upgrade the crate power supply if necessary.
PMC Slot Overloading
They populate both PMC sites with high-power modules, exceeding the board’s thermal limits. The SBC overheats and throttles the CPU, causing control cycle jitter.
- Quick Fix: Ensure adequate airflow over the PMC modules. If the board is in a sealed enclosure, you may need to derate the CPU speed or use low-power PMC cards.
BIOS Configuration Loss
The onboard battery dies, wiping the CMOS settings. The rookie tries to reflash the firmware instead of fixing the battery.
- Field Rule: Replace the onboard 3.6V battery. After replacement, you’ll need to reset the BIOS boot order to IDE0 and disable unnecessary peripherals like the floppy controller.
VMIVME-7740-840
Commercial Availability & Pricing Note
Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.
