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GPIB-USB Controller 3.x Manual

  1. Features
  2. Installation
  3. Device Mode
  4. Controller Mode · (Example)
  5. Commands
  6. Sample Programs
  7. DIP Switch Settings
  8. Technical Specifications
  9. Frequently Asked Questions

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

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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.

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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.

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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:

id? ? Command typed by user
"HP54201A" ? Response from DSO
ser? ? Command typed by user
"2738A02659" ? Response from DSO
plot; ? Command typed by user
lbdf;sc0,575,0,367... ? Response from DSO

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

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Commands

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

Command Description
++addr 0-31 Tell controller which device to address [Default set by DIP switch]
++addr Query currently configured device address
++clr Issue device clear
++eoi 0|1 Enable (1) or disable (0) EOI with last byte. Default is 0.
++eoi Query current EOI setting
++eos 0|1|2|3 EOS terminator — 0:CR+LF, 1:CR, 2:LF, 3:None. Default is 0.
++eos Query current EOS setting
++ifc Issue interface clear
++loc Return device to local mode
++spoll Read status byte by serial polling the device
++srq Query status of SRQ line. 0: Not asserted, 1:Asserted
++trg Issue device trigger
++ver Query GPIB-USB controller version
++help Print help about commands

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:

++addr 7 ? Tell controller to address instrument at GPIB address 7
id? ? Issue command
"HP54201A" ? Response from instrument at address 7
++addr 8 ? Tell controller to address instrument at GPIB address 8
*idn? ? Issue command
"HP1651B" ? Response from instrument at address 8

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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.

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DIP Switch Settings

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

Mode DIP Switch #6
GPIB-USB Controller operates in Device Mode OFF
GPIB-USB Controller operates in Controller Mode ON
GPIB Address DIP Switch
#1 #2 #3 #4 #5
0 OFF OFF OFF OFF OFF
1 ON OFF OFF OFF OFF
2 OFF ON OFF OFF OFF
3 ON ON OFF OFF OFF
4 OFF OFF ON OFF OFF
5 ON OFF ON OFF OFF
6 OFF ON ON OFF OFF
7 ON ON ON OFF OFF
8 OFF OFF OFF ON OFF
9 ON OFF OFF ON OFF
10 OFF ON OFF ON OFF
11 ON ON OFF ON OFF
12 OFF OFF ON ON OFF
13 ON OFF ON ON OFF
14 OFF ON ON ON OFF
15 ON ON ON ON OFF
16 OFF OFF OFF OFF ON
17 ON OFF OFF OFF ON
18 OFF ON OFF OFF ON
19 ON ON OFF OFF ON
20 OFF OFF ON OFF ON
21 ON OFF ON OFF ON
22 OFF ON ON OFF ON
23 ON ON ON OFF ON
24 OFF OFF OFF ON ON
25 ON OFF OFF ON ON
26 OFF ON OFF ON ON
27 ON ON OFF ON ON
28 OFF OFF ON ON ON
29 ON OFF ON ON ON
30 OFF ON ON ON ON
31 ON ON ON ON ON

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Technical Specifications

Supported OS Windows 98/ME/2000/XP, Mac OS 8/9/X, Linux
Supported Standards USB 1.1, USB 2.0, IEEE 488.1
Unsupported GPIB modes Parallel Poll, Pass Control
Power USB bus powered device, +5V, 100mA (max)
Support for USB hubs Self-powered and bus-powered hubs
Data transfer rate 115,200 baud
Data format 8-bit data, no parity, 1 stop bit, hardware flow control
Configuration DIP switch for GPIB address and Device mode
Indicators Power, Device mode, Data
Dimensions 2.8 inch (L) x 2.5 inch (W) x 1.0 inch (H)

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Frequently Asked Questions

See FAQ.