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Introduction

The A395D is an expansion board for the V2495 that provides 8 bidirectional LEMO 00 channels. Each channel can be individually configured as input or output, with selectable NIM or TTL signal levels.

A395D Board

The board can be installed in expansion slots D, E, or F of the V2495 mainboard.

Product link: CAEN A395D

Pin Description

IN_0 Input 1 bit BIT
IN_1 Input 1 bit BIT
IN_2 Input 1 bit BIT
IN_3 Input 1 bit BIT
IN_4 Input 1 bit BIT
IN_5 Input 1 bit BIT
IN_6 Input 1 bit BIT
IN_7 Input 1 bit BIT
SEL Input 1 bit BIT
OE Input 1 bit BIT
OUT_0 Output 1 bit BIT
OUT_1 Output 1 bit BIT
OUT_2 Output 1 bit BIT
OUT_3 Output 1 bit BIT
OUT_4 Output 1 bit BIT
OUT_5 Output 1 bit BIT
OUT_6 Output 1 bit BIT
OUT_7 Output 1 bit BIT
INx (IN0-IN7) Input 1 bit

Input signals from FPGA logic (8 total). When the corresponding channel is configured as output (OUT/IN = 1), the INx value is driven to the LEMO connector.

When the channel is configured as input, INx is ignored.

OUTx (OUT0-OUT7) Output 1 bit

Output signals to FPGA logic (8 total). When the corresponding channel is configured as input (OUT/IN = 0), the OUTx pin provides the signal received from the LEMO connector.

When the channel is configured as output, OUTx reflects the INx value.

NIM/TTL Input 1 bit

Signal level selection (8-bit vector, one bit per channel).

  • LOW (0): NIM signal levels
  • HIGH (1): TTL signal levels

Set according to your external equipment requirements.

OUT/IN Input 1 bit

Direction control (8-bit vector, one bit per channel).

  • LOW (0): Channel is an input (LEMO → FPGA via OUTx)
  • HIGH (1): Channel is an output (FPGA via INx → LEMO)

Properties

Property window

Socket Socket

Select the socket hosting the expansion board

Selects the expansion socket where the A395D is installed. Available options: D, E, F. Must match the physical installation location on the V2495 mainboard.

Default: D

Options: D E F

Usage

Bidirectional Operation

Each of the 8 channels on the A395D can be configured as either input or output:

  ┌──────────────────────────────────────────────────────────────────┐
│                    A395D Bidirectional Flow                      │
│                                                                  │
│   ┌─────────────┐                  ┌─────────────┐               │
│   │   FPGA      │═══► INx ════════►│             │               │
│   │   Logic     │                  │   A395D     │◄══► LEMO 00   │
│   │             │◄══ OUTx ◄════════│  (8 ch)     │    Connector  │
│   │             │═══► OUT/IN ─────►│             │               │
│   │             │═══► NIM/TTL ────►│             │               │
│   └─────────────┘                  └─────────────┘               │
└──────────────────────────────────────────────────────────────────┘

Direction Control (OUT/IN)

The OUT/IN signal controls the direction of each channel:

OUT/IN State Channel Direction
LOW (0) Channel is an INPUT (external → FPGA)
HIGH (1) Channel is an OUTPUT (FPGA → external)

When configured as input: data from the LEMO connector appears on the OUTx pin. When configured as output: data from the INx pin is driven to the LEMO connector.

Signal Level Selection (NIM/TTL)

The NIM/TTL signal selects the electrical standard:

NIM/TTL State Signal Type
LOW (0) NIM (negative logic)
HIGH (1) TTL (positive logic)

Timing Diagram

Expansion Socket Selection

Socket Description
D Expansion slot D
E Expansion slot E
F Expansion slot F

Signal Characteristics

Parameter Value
Channels 8
Connector type LEMO 00
Signal types NIM or TTL (selectable)
Direction Bidirectional (per channel)

Resources & Timing

  • Latency: Minimal (I/O buffer delay only)

  • Throughput: 8 bidirectional channels at FPGA clock rate

  • Per-channel direction control
  • Per-channel NIM/TTL selection
  • LEMO 00 front panel connectors

Supported Boards

  • V2495