VISA Keyboard.NET Program

 

General

You can use ICS Electronics' VISA Keyboard.NET Program with any VXI-11 compatible VISA library to communicate with anyone's GPIB or VXI-11 device. (See notes 1 and 2 below for VISA restrictions.) The VISAkybd.NET program lets you open a session to a TCPIP address and inst number, to a GPIB device or to a predefined VISA Resource.

The VISAkybd.NET program will run in any Windows computer that has Microsoft.NET Framework 2.0 installed. VISAkybd.NET requires that an Agilent or National Instruments VISA library be installed on the computer.

 

Operation

Start the VISAkybd.NET program by double clicking on the program name. When the main form opens, use the radio buttons in the Instrument Resource Address frame to select the type of Instrument Resource to open. For a TCPIP resource, enter the instrument's iP address and use the pulldown arrow to select an inst number. Most LAN instruments will respond to an *IDN? query at inst0. For a GPIB device, enter the device's GPIB primary address. The GPIB device should be connected to a controller defined as GPIB0. For a VISA Resource, use the pulldown arrow to expose the list of VISA resources. The list will contain resources defined in NI's Measurement and Automation Explorer or Agilent's Connection Expert plus other VISA resources discovered by the VISAkybd.NET program. Highlight one of the listed resources to select it. When done, click on the Open Resource button to open the VISA session to your selected device.

At this time, all controls should be enabled on the main form. Each control has a tool tip help message which appears when you hold the mouse cursor on the control. This message describes the control's function.

 

Sending and Receiving Messages

The default control settings will let you communicate directly with the device or instrument by placing a device message in the Device Command box and then clicking on the Send button. The Device Command box has a pulldown arrow which exposes three, frequently used, IEEE-488.2 commands. All of ICS's GPIB and VXI-11.3 Interfaces are IEEE-488.2 compatible devices and respond to these queries. LXI instruments will respond to the *IDN? query. Just select a query and click Send to query the device.

If the message contains a question mark '?' character, the response will be automatically displayed in the Device Response window. To manually read a device response message, click on the Read Device Response button. The Display all characters and Display Character Count options let you see and count all of the characters in the received message. Non-printable characters like linefeed characters show up as dark bars, squares or as blank spaces.

 

Message Terminators

The Message Terminator options let you modify the message terminators for send and receive. The LF (linefeed) box is checked by default because a linefeed is the IEEE-488.2 specified message terminator. Unchecking LF and checking CR changes the terminator to a carriage return character. Checking both boxes adds a carriage return-linefeed character sequence to each message. EOI or END is also asserted on the last character of each message.

 

Instrument Commands

The Instrument Commands frame has buttons for sending unique GPIB or VXI-11 commands to the device or instrument. The Lock and Unlock buttons are used to manually lock a VXI-11.3 instrument so other clients will not be able to access it while you have it locked. Be sure to unlock it when done else the instrument or the VISA layer will have to be reset or power cycled to remove the lock. If Auto Lock is checked, the Lock and Unlock buttons will be disabled. The instrument will be automatically locked when a command is sent to the instrument and unlocked when the response is read or when the command has been completed.

The other buttons in the Instrument Commands frame let you send 488.1 type Device Clear or Device Trigger commands to the instrument. Note that 488.2 compatible instruments need to be armed before being send a Device Trigger. Check the instrument's manual for its use of the SCPI INITATE command and arming requirements. The Serial Poll button Serial Polls a GPIB device or sends a device_read_stb rpc to a VXI-11.3 instrument.

 

IDN Message Loop

The IDN Message Loop controls run a timing loop that sends the *IDN? query to the selected device every 250 ms. Pressing the Run Loop button inserts the *IDN? query in the Device Command window and starts the loop. While the loop is running, a Loop Count window appears in the blank area to the right of the loop controls. The count increments once for each query loop. Clicking Stop Loop stops the IDN message loop and clears the loop counter.

 

Device Command Loop

The Device Command Loop controls run a timing loop that sends the command(s) in the Device Command window to the selected device every 250 ms. Enter a command in the Device Command window and pressing the Run Loop button to start the loop. If the command contains a question mark, the loop will automatically read the response. While the loop is running, a Loop Count window appears in the blank area to the right of the loop controls. The count increments once for each query loop. Clicking Stop Loop stops the Device Command Loop and clears the loop counter.

Depending upon the device's command vocabulary, you can concatenate several commands in the Device Command window to produce some repeated affects. Examples are:

BO1 1; BO1 0 - Pulses a digital IO line on an ICS 48x3 or 80x3 Interface.

C 1; D 5.0 ; A?1; D 0 - Sets analog output to 5 Vdc, takes a reading and sets the analog output back to 0 Vdc.

 

Notes:

Note 1. Agilent's VISA library lets you send VXI-11.2 and VXI-11.3 commands. National Instruments' VISA limits you to using just VXI-11.3 commands. This means that National Instruments' VISA is good for controlling most VXI-11 instruments and interfaces, Agilent's VISA library should be used when controlling an GPIB Gateway like ICS's Model 8065. GPIB Gateways are VXI-11.2 devices.

Note 2. LXI instruments may not required to be fully VXI-11 compatible and they may not be IEEE-488.2 compliant so an LXI instrument may not respond to other 488.2 Common Commands beyond '*IDN?'. Check your instrument's specification for IEEE-488.2 and VXI-11 compliance. VXI-11.3 compatible instruments are specified to be fully IEEE-488.2 and VXI-11.3 compliant.

 

 

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Last updated: 04-12-2011