📋 Product Overview

The ZYGO ZMI-2002 is a dual-axis 6U VME measurement board developed for high-precision interferometric measurement systems. It is part of the ZMI 2000 family and provides two measurement axes on a single VME board, reducing the number of backplane slots required compared with separate single-axis measurement hardware.

The board receives reference and measurement signals from an interferometric measurement system and provides digital position, velocity, timing, and error-status information to the host control system. The ZMI-2002 supports VMEbus and P2 interfacing and can be integrated with servo cards, motion controllers, and other VME-based equipment.

The exact eBay listing supplied for this product identifies the unit as ZYGO ZMI-2002 Dual Axis 6U VME Measurement Board and lists the condition as New.

⚙️ Key Features

• Dual-axis measurement on one 6U VME board
• Designed for ZYGO interferometric measurement systems
• 6U VMEbus form factor
• VMEBus Specification Revision C.1
• A16 or A24 addressing
• D16 or D32 data transfer
• 36-bit two’s-complement position format
• 32-bit two’s-complement velocity format
• 25 ns time resolution
• Fiber-optic reference and measurement signal inputs
• Clock-in / clock-out system synchronization
• P2 interface for system expansion and integration
• Error monitoring for reference, measurement, velocity, acceleration, and overflow conditions

📊 Product Datasheet

Parameter	Specification
Brand	ZYGO
Model	ZMI-2002
Product Type	Dual-Axis VME Measurement Board
Board Format	6U VME
Measurement Axes	2
VME Compliance	VMEBus Specification Revision C.1
Addressing	A16 / A24
Data Transfer	D16 / D32
Position Format	36-bit, two’s complement
Velocity Format	32-bit, two’s complement
Time Format	32-bit, two’s complement
Time Range	107.4 seconds
Time Resolution	25 ns
Optical Signals	Reference and Measurement
Synchronization	Clock In / Clock Out
P2 Interface	32-bit P2 bus
Power Requirement	+5 V ±5% @ 3.5 A
Number of Axes	2 per board
Listing Condition	New

These values come from the ZMI 2000 series datasheet and technical references. The +12 V specification shown in some listings applies to the ZMI PC variant and should not be automatically assigned to the ZMI-2002 VME board.

🔌 Operating Function

The ZMI-2002 is essentially a measurement-processing interface between the optical interferometer and the VME-based control computer.

A typical measurement chain is:

Interferometer → Reference/Measurement Optical Signals → ZMI-2002 → VME/P2 Data Interface → Host Controller

The board processes the measurement information and makes digital position and velocity data available to the host system. Its 36-bit position format and 25 ns time resolution provide the data structure needed for high-precision motion and metrology applications.

The dual-axis architecture is particularly useful where two measurement axes need to be handled within the same VME chassis. ZYGO’s documentation specifically describes the ZMI-2002 as a two-axis board, while the ZMI-2001 provides one axis.

🧭 Measurement & Synchronization

The ZMI-2002 provides several status and synchronization functions that are important in precision measurement systems.

The documented error-status categories include:

• Reference signal condition
• PLL and DLL status
• Missing measurement signal
• Dropout and glitch detection
• Board-defined velocity errors
• User-defined velocity errors
• Acceleration conditions
• 32-bit overflow
• 36-bit overflow

System synchronization can be configured using clock input or clock output. This allows the measurement board to participate in a larger synchronized VME measurement architecture.

🔧 Installation & Configuration

1. Verify the VME System

Confirm that the target chassis supports a 6U VME board and that the available slot provides the required power.

The ZMI-2002 is not intended to operate as a standalone measurement instrument outside its associated VME system.

2. Check Optical Connections

Before installation, verify the reference and measurement optical connections.

Keep optical connectors clean and protected from dust. Contamination or damaged fiber connections can result in missing or unstable measurement signals.

3. Install the VME Board

With system power removed, insert the ZMI-2002 carefully into the appropriate 6U VME slot.

Make sure the board is correctly aligned with the VME backplane connectors before securing the front-panel hardware.

4. Configure the VME Interface

The host system should be configured according to the required VME addressing and data-transfer mode.

The ZMI-2002 supports A16/A24 addressing and D16/D32 data transfers.

5. Configure P2 Integration

The P2 interface can be used to connect the measurement board with compatible servo or motion-control hardware.

The ZMI 2000 documentation notes that multiple boards can be bus-connected through the P2 interface, supporting larger multi-axis measurement systems.

6. Perform a Functional Test

After powering the system:

1. Confirm the VME board is recognized.
2. Check reference and measurement signal status.
3. Verify clock synchronization.
4. Confirm position data.
5. Check velocity information.
6. Review error-status registers.
7. Compare measured values against the system’s reference equipment.

Do not return a precision motion system to production until the measurement feedback has been verified.

🏭 Application Scenarios

The ZMI-2002 is suited to applications where precise displacement feedback is required.

Typical environments include:

• Precision positioning systems
• Semiconductor manufacturing equipment
• Semiconductor stage metrology
• Precision machine tools
• Optical measurement systems
• Motion-control test systems
• Coordinate measurement equipment
• Scientific instrumentation
• High-accuracy positioning platforms
• VME-based metrology systems

A published VME metrology system design, for example, identifies the Zygo ZMI 2002 as a dual-axis register-based VME measurement board used within a precision metrology architecture.

🔬 Why the Dual-Axis Design Matters

For a multi-axis measurement system, the number of VME slots can become a practical limitation.

The ZMI-2002 combines two measurement axes on one 6U VME board. This reduces the number of boards needed for a two-axis configuration and leaves additional VME slots available for timing, processing, motion-control, or interface hardware.

The ZMI 2000 architecture can also be expanded using multiple measurement boards. The documented P2 interface supports data rates up to 7.7 MHz, with systems capable of handling multiple axes through the appropriate architecture.

🧰 Maintenance Recommendations

Because this board is normally used in precision metrology equipment, maintenance should include both the electronics and the optical measurement chain.

Recommended checks:

• Keep the VME chassis clean and dry.
• Check VME connector condition during scheduled maintenance.
• Inspect optical connectors for contamination.
• Protect unused optical ports from dust.
• Verify stable +5 V supply voltage.
• Check VME communication and register access.
• Monitor reference and measurement error flags.
• Verify synchronization signals.
• Keep the host-system software and configuration backed up.
• Record the original board configuration before replacement.

For a spare board, use ESD-safe packaging and avoid exposing the optical/electronic interfaces to unnecessary contamination.

❓ Frequently Asked Questions

Is the ZMI-2002 a PLC module?

No. It is more accurately described as a dual-axis VME measurement board used in precision interferometric measurement systems. The eBay seller categorizes it as a PLC processor module, but the technical documentation identifies its actual function as a ZMI 2000 measurement board.

How many measurement axes does one ZMI-2002 provide?

The ZMI-2002 provides two measurement axes on one 6U VME board.

What is the position data format?

The documented position format is 36-bit two’s complement. Velocity is represented using a 32-bit two’s-complement format.

What is the time resolution?

The ZMI 2000 documentation specifies a 25 ns time resolution.

What voltage does the ZMI-2002 require?

The documented requirement is +5 V ±5% at 3.5 A for the ZMI-2001, ZMI-2002, and ZMI PC family. The +12 V specification in the same datasheet is associated with the ZMI PC configuration and should not be assumed for the ZMI-2002.

Does the ZMI-2002 use VMEbus?

Yes. It is a 6U VME board and supports VMEBus Revision C.1, A16/A24 addressing, and D16/D32 data transfer.

Is this exact eBay item new?

Yes. The supplied eBay listing identifies the ZMI-2002 as New.

🔄 Related ZYGO Models

Related products in the ZMI 2000 family include:

1. ZYGO ZMI-2001 — Single-Axis 6U VME Measurement Board
2. ZYGO ZMI-2002 — Dual-Axis 6U VME Measurement Board
3. ZYGO ZMI PC — Single-Axis ISA Measurement Board
4. ZYGO ZMI 2000 Series Measurement Boards
5. ZYGO ZMI interferometer systems
6. ZYGO laser interferometer components
7. ZYGO precision measurement interfaces
8. ZYGO optical metrology hardware
9. ZYGO VME measurement electronics
10. ZYGO multi-axis measurement configurations

The ZMI-2001 and ZMI-2002 should not be treated as interchangeable: the documented difference is one measurement axis versus two measurement axes per board.

📝 Application Summary

The ZYGO ZMI-2002 is a specialized dual-axis 6U VME measurement board for high-precision interferometric measurement systems. Its VMEbus architecture, dual-axis design, 36-bit position format, optical reference/measurement inputs, and synchronization functions make it suitable for precision motion and metrology platforms where conventional PLC analog inputs would not provide the required measurement architecture.

For replacement projects, the most important checks are the exact ZMI-2002 board configuration, VME chassis compatibility, optical interface arrangement, host software, P2 connections, and system synchronization requirements.

Reference Model: ZMI-2002
Product Type: Dual Axis 6U VME Measurement Board
Manufacturer: ZYGO Corporation