Keysight / Agilent / HP E2251A C-Size VXI M-Module Carrier

The Keysight E2251A is a C-size VXI M-Module carrier designed to host up to six M-Modules, each with independent logical addresses. It provides the electrical and mechanical interface between the VXIbus system backplane and installed M-Modules, enabling direct integration into VXI-based test and measurement systems. The carrier supports VXI Specification Revision 1.4 and offers programmable interrupts for each M-Module slot, with automatic daisy-chain interrupt acknowledge that bypasses empty slots.

– Technical Specifications

• Form Factor: C-size, single-slot VXI M-Module carrier
• M-Module Capacity: Up to six M-Modules per carrier (five M-Modules recommended for optimal cabling access)
• Logical Addressing: Separate address per M-Module; configured via onboard switches. Addresses must be multiples of 8 (8, 16, 24, …, 256) when using E1406 Command Module. Address 0 disables the slot
• VXI Compliance: Revision 1.4
• Memory Space: A16 and A24 memory space distribution for M-Module registers
• Interrupt Handling: Programmable interrupts with automatic daisy-chain acknowledge across all six slots. Converts Type B and C interrupts to standard VXI ROAK (Release on Acknowledge) by default
• System Scalability: Up to 31 M-Modules with E1406A Command Module; up to 255 M-Modules with embedded controllers, E8491B, or MXIbus solutions
• EEPROM Identification: Reads and maps M-Module identification data (Manufacturer ID, Device Type, Status) into standard VXI registers
• Dimensions: 12 × 14 × 5 inches (approximate)
• Weight: 5.2 lbs (approximate)

– Key Features

• Independent logical address assignment for each M-Module
• Automatic interrupt acknowledge daisy-chain with empty-slot bypass
• VXI backplane access with full register configuration support
• I/O space and memory access via standard VXI interface
• Power distribution for all installed M-Modules

– Compatibility & Integration

The E2251A supports a broad range of M-Module types including switch matrices, relay multiplexers, digital I/O modules, breadboard M-Modules, and RS-232 interface modules. Compatible modules include the E2259A, E2261A, E2270A, E2271A, E2272A, E2273A, E2274A, E2290A, and E2291A. Integration with E1406A Command Modules, embedded VXI controllers, E8491B interfaces, and MXIbus solutions enables multi-carrier configurations for expanded system capacity.