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NanoDispense Dispenser Head Communications Interface

The NanoDispense head is a self-contained dispense mechanism with its own microscope, camera, and microcomputer. The designer has two choices:

  • The head can be directly driven from the host, with the user providing all of the software on the host side.

  • The host can use the services of a COM based DLL that can be called from Visual Basic, C++, or C#.

A Visual Basic 6.0 demo program is provided for users running Windows. The VB demo uses the COM DLL and so provides an example of its use. The DLL exposes properties, methods, and events in the usual fashion. The VB demo has a complete user interface and can capture and store images from the head camera for debugging and protocol design. It can be used directly in simple applications, but its main purpose is to provide an starting point for further integration. The VB source code is provided.

Except for wishing to run the demo program, the host may use any operating system. For those interested, the microprocessor in the head runs Linux.

Two physical interfaces are provided on the head: Ethernet and RS-232. The same information is available on both but the speed limitations of RS-232 preclude passing complete images in a reasonable time. Images from the head's camera are used during debugging and when you wish to have images for publication, so the speed limitations of RS-232 are not a serious issue in ordinary operation.

The Ethernet interface uses an RJ45 modular jack.

The RS-232 interface uses a D9S that connects one-to-one with the connector on a standard PC, so no null-modem crossover is required.

For the Ethernet interface, the general layering is

  • application program
  • communications DLL
  • SOAP
  • HTML
  • TCP/IP
  • Ethernet physical connectivity

For the RS-232 interface, it is simpler:

  • application program
  • communications DLL
  • RS-232 physical connectivity

A small number of direct opto-isolated input/output lines are provided for PLC users. These will be used only when the host, say a PLC, can not easily parse messages from the head. These lines are not recommended when a competent machine is available on the host side.