1. Controller Mode · (Example)

Nov 16, 2016  How To Control Your Instruments From A Computer: It’s Easier Than You Think. 36 thoughts on “ How To Control Your Instruments From A Computer. Para instalar a interface GPIB-USB, encaixe o conector USB da interface GPIB-USB em uma porta USB do computador. Antes de conectar a interface GPIB-USB em dispositivos GPIB, certifique-se de que o computador e os dispositivos GPIB estejam em um mesmo potencial de terra.

Turn any computer with an USB port into a GPIB controller with this low cost GPIB-USB controller! Use this controller to control, and to download screen plots and data from, Oscilloscopes, Logic Analyzers, Spectrum Analyzers and other GPIB enabled instruments.

Features

• Drivers for Windows 98/ME/2000/XP, Mac OS-8/9/X, Linux
• Device and Controller modes
• Support for multiple devices
• Driver provides virtual COM port to send and receive data
• Powered by USB; no power supply needed
• No GPIB cable needed; controller plugs on to instrument
• USB 1.1 and USB 2.0 compatible
• Standard USB (B) and IEEE 488 (Male) connectors

Installation

To install the controller do the following:

1. Download drivers for FT232BM from www.ftdichip.com/Drivers/VCP.htm
2. Connect controller to computer using an USB (A-B) cable
3. Install drivers according to www.ftdichip.com/Documents/InstallGuides.htm
4. Plug controller directly, or using a GPIB cable, on to the GPIB connector of the instrument
5. Configure the virtual COM port to 115,200 baud, 8-bit data, no parity, 1 stop bit and hardware (RTS/CTS) flow control
6. Open the port using any terminal program (e.g. HyperTerminal, Tera Term Pro)
7. Configure the terminal program to always send Line Feed with Carriage Return
8. Send commands or receive data

To render screen plots graphically we recommend any of the following software:

• 7470.exe — an excellent open source application.
• PrintCapture — a full-featured commercial application. 30-day free trial version available.
• Plottergeist — another full-featured commercial application.

Device Mode

In Device mode, the GPIB-USB Controller acts as another device on the GPIB bus. In this mode, the GPIB-USB Controller can act as a GPIB Talker or GPIB Listener only. Since the GPIB-USB Controller is not a System Controller in Device mode, it expects to receive GPIB commands from the Controller-In-Charge (CIC). On power up in Device mode the GPIB-USB Controller is configured as a GPIB Listener. All data received by the GPIB-USB Controller over the GPIB port is passed along to the USB port. When you are expecting to receive data from the USB device, address the GPIB-USB Controller to talk, and all data received over the USB port is passed along to the GPIB port. When you are ready to send data to the USB device again, address the GPIB-USB Controller to listen.

Note: Use Device mode to download screen plots from instruments.

Controller Mode

In Controller mode, the GPIB-USB Controller acts as a System Controller. On power up in Controller mode the GPIB-USB Controller asserts IFC to become Controller-In-Charge (CIC). After the GPIB-USB Controller becomes CIC, it addresses the GPIB instrument to talk. The GPIB-USB Controller always asserts REN when addressing devices. All data received over the GPIB port is passed along to the USB port. When GPIB-USB Controller receives any character over the USB port it addresses the GPIB instrument to listen and passes along the received data. It remains in this mode until the Line Feed character (0x0A) is received over the USB port, at which time the GPIB-USB Controller re-addresses the GPIB instrument to talk.

Note: Use Controller mode to send commands to instruments. Terminate commands with a Line Feed character (0x0A) to notify GPIB-USB Controller to address the GPIB instrument to talk after sending the command. This is required to receive any output from the instrument.

Example

The GPIB-USB controller was installed and configured as described earlier. It was plugged onto the GPIB port of a HP 54201A Digital Storage Oscilloscope. User opened the virtual COM port with HyperTerminal and performed the following dialogue:

As you can see from the above example, the GPIB-USB controller makes communicating with any GPIB instrument easy and intuitive.

Commands

When the GPIB-USB controller is in Controller mode it understands the following commands send over virtual COM port.

You are most likely to use the if more than one instrument is connected to the GPIB-USB controller. In such cases you can use the ++addr command to address each instrument in turn, before talking to it. For example:

Sample Programs

Following sample programs demonstrate how to programmatically send and receive data from the GPIB-USB controller. They were developed using Microsoft Visual Studio Express Edition on Windows XP SP2 and tested using FTDI driver version 2.00.00.

• C# sample (Requires Microsoft .NET 2.0)
• Visual Basic.NET sample (Requires Microsoft .NET 2.0)

DIP Switch Settings

Disconnect all cables and power down before changing DIP switch settings.

Technical Specifications

Frequently Asked Questions

See FAQ.

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How is Prologix GPIB-USB controller different from other vendors'? While Prologix GPIB-USB controller provides many of the same features as GPIB-USB controllers from other vendors, it is much easier to use. Prologix GPIB-USB controller provides a virtual serial interface to communicate with instruments, while handling all GPIB protocol details for you. As a result, you can easily communicate with your instruments using a simple terminal program instead of having to write custom programs using a vendor supplied GPIB library. Please see the for a complete list of features.

Is Prologix GPIB-USB controller compatible with NI LabVIEW, Agilent VEE, and other test frameworks? Prologix GPIB-USB controller provides a virtual serial interface to communicate with instruments, while handling all GPIB protocol details for you.

Any test framework, or programming environment, that provides access to serial ports is compatible with Prologix GPIB-USB controller. For example, you may use NI LabVIEW Serial VIs or NI VISA VIs to communicate with the controller through the virtual serial port. Another option is to use the FTDI D2XX drivers. FTDI has for communicating with the controller using D2XX drivers. Will my NI LabVIEW, or Agilent VEE, programs work unmodified with Prologix GPIB-USB controller? Probably not. Prologix GPIB-USB controller provides a virtual serial interface to communicate with instruments, while handling all GPIB protocol details for you.

Programs that expect a GPIB interface (such as NI 488.2 interface) must be modified to use the serial interface to work with Prologix GPIB-USB controller. Can Prologix GPIB-USB controller talk to multiple instruments?

You specify the GPIB address of the instrument to address using the addr command. All subsequent device commands are sent to the specified address. When you want to address a different instrument, issue another addr command with the new address. How do I download screen plots from instruments?