How to communicate with instruments that support GPIB. Gianfranco Miele, Ph.D

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1 How to communicate with instruments that support GPIB Gianfranco Miele, Ph.D

2 Requirements Controller IEEE-488 Matlab Instrument control toolbox November 11, 2014

3 IEEE-488 history It is a short-range digital communication bus developed to be used with automated test equipment. It was proposed by Hewlett-Packard in In 1975 standardized the bus as IEEE-488. The standard was revised and redesignated as IEEE in It is also known as HPIB (Hewlett-Packard Interface Bus) or GPIB (General Purpose Interface Bus). In 1987, IEEE introduced Standard Codes, Formats, Protocols, and Common Commands, IEEE While IEEE defined the hardware and IEEE defined the protocol, there was still no standard for instrument-specific commands. In 1990 was introduced SCPI (Standard Commands for Programmable Instruments). November 11, 2014

4 Interface Interface BUS Interface Interface IEEE-488 overview Device Device Device Device November 11, 2014

5 IEEE-488 overview Devices connected to the IEEE-488 bus can be divided in three main categories: Listener It is a device that can receive data from the bus when instructed by the Active Controller. Talker It transmits data on to the bus when instructed.

IEEE-488 overview Devices connected to the IEEE-488 bus can be divided in three main categories: Controller It can set up a talker and a group of listeners so that it is possible to send data between

6 IEEE-488 overview Devices connected to the IEEE-488 bus can be divided in three main categories: Controller It can set up a talker and a group of listeners so that it is possible to send data between groups of devices as well. It is possible to have several Controllers on the bus but only one may be active at any given time. The Active Controller may pass control to another controller which in turn can pass it back or to another controller.

7 Bus configuration The standard allows a maximum of 15 devices to be connected on the same bus. Maximum separation of 4 m between any two adjacent devices and an average separation of 2 m over the entire bus Maximum cable length of 20 m

8 Instrument control toolbox Instrument Control Toolbox lets you connect MATLAB directly to instruments such as oscilloscopes, function generators, signal analyzers, power supplies, and analytical instruments. The toolbox connects to your instruments via instrument drivers such as IVI and VXIplug&play, or via text-based SCPI commands over commonly used communication protocols such as GPIB, VISA, TCP/IP, and UDP.

9 Test & Measurement tool The Test & Measurement Tool displays the resources (hardware, drivers, interfaces, etc.) accessible to the toolboxes that support the tool, and enables you to configure and communicate with those resources. This tool enables you to do the following Search for available hardware and drivers Create instrument objects Connect to an instrument Configure instrument settings Write data to an instrument Read data from an instrument Save a log of your session as a file

10 Test & Measurement tool The Test & Measurement Tool displays the resources (hardware, drivers, interfaces, etc.) accessible to the toolboxes that support the tool, and enables you to configure and communicate with those resources. In order to start the Test & Measurement tool type tmtool

11 tmtool Expand Hardware

12 tmtool Expand GPIB

13 tmtool Click on Scan Installed controllers will be enlisted.

14 tmtool Select the controller that you want to use and click on Scan in order to detect the devices connected to the bus.

15 tmtool Info about the devices connected to the bus will be enlisted. In particular primary address and identification will be shown.

16 tmtool Selecting the device that you want to control, the following window will appear.

17 tmtool By clicking on Connect you can start to communicate with the device. Your message has to be typed in Data to write textbox. If you type a Query message, the response will appear in Response textbox.

18 tmtool All the bus activity is enlisted here.

19 tmtool By clicking on Disconnect you can close the communication.

20 Matlab commands First of a GPIB object has to be created by typing the following command obj = gpib('vendor',boardindex,primaryaddress) where VENDOR is the controller manufacturer. In this case 'ni'; BOARDINDEX is the controller address. In this case 0; PRIMARYADDRESS is the address of the instrument with which you want to communicate. In the previous example it is equal to 4;

21 Matlab commands Successively you need to set some communication parameters by typing the following command set(obj,'outputbuffersize',n,'inputbuffersize',m,'byteorder','littleendian'); Where N and M are the output and input buffer size respectively. These value has to be expressed in byte.

22 Matlab commands After these preliminary setting operations, you can start the communication by typing fopen(obj); You can send a message to the instrument fprintf(obj,'string'); You can read the response of the instrument s=fscanf(obj,'%c'); You can close the communication fclose(obj);

23 Device message standard in IEEE In the last edition of the standard some common device message are defined: *IDN? *RST *TST? *CLS Identification query Reset command Self-test query Clear status Please read the instrument manual in order to know the response to these commands.

24 SCPI command syntax SCPI command syntax for remote interface programming: Square brackets ( [ ] ) indicate optional keywords or parameters. Braces ( { } ) enclose parameters within a command string. Triangle brackets ( < > ) enclose parameters for which you must substitute a value. A vertical bar ( ) separates multiple parameter choices.

Using MATLAB with KEITHLEY Instrument Devices through GPIB Page 1 of 6

Using MATLAB with KEITHLEY Instrument Devices through GPIB Page 1 of 6 Preface Using MATLAB with Instrument Devices through GPIB Page 1 of 6 This application note is intended to help the user in setup and configuration of Keithley Instrument products through Keithley GPIB