> Sending SCPI Commands
> SCPI commands can be sent to the instrument through any Virtual Instrument Software Architecture (VISA) controller. VISA is a commonly used API in the Test and Measurement industry for communicating with instruments from a PC. The physical connection between the PC and the instrument is USB or Ethernet. NI-VISA is the National Instruments implementation of the VISA I/O standard. Information and downloads are available at: http://www.ni.com/visa/
> The following example describes the verification that a VISA controller can interact with the instrument. The images shown and the instructions for your instrument and software may differ from the examples.
> USB Connectivity

> 1. | On the PC, run NI Measurement & Automation Explorer or VISA Interactive Control and double-click on the TMC Class instrument.

> Figure 1-4. NI Measurement & Automation Explorer

> 2. | Verify that the USB Settings list the correct Manufacturer, Model, and Serial Number, as shown in the example below.

> NI VISA Interactive Control USB Configurations / Settings Tab

> 3. | Select the Input/Output Basic I/O tab and execute the default *IDN? Query. If the PC is connected to the instrument the command returns the following information from the Buffer: manufacturer name (“Anritsu”), model number/options, serial number, and firmware package number, as shown in the example below.

> NI VISA Interactive Control USB Basic I/O Tab

> Ethernet Connectivity

> 1. | On the PC, run NI Measurement & Automation Explorer or VISA Interactive Control and create a new LAN Resource under Network Devices. Add the TCP/IP resource using a Manual Entry of Raw Socket, as shown in the example below.

> NI VISA Interactive Control LAN Resource Addition Using Raw Socket

> 2. | Enter the IP address that the instrument has acquired (go to System, Status, Connectivity Info). Enter the port number as 9001, as shown in the example below.

> NI VISA Interactive Control LAN Resource Settings of IP Address and Port Number

> NI VISA Interactive Control LAN Resource Validated

> 3. | Select the Configuration I/O settings tab and verify that the Termination Methods are set as shown in the example below.

> NI VISA Interactive Control LAN Resource I/O Termination Method Settings

> 4. | Select the Input/Output Basic I/O tab and execute the default *IDN? Query. If the PC is connected to the instrument the command returns the following information from the Buffer: manufacturer name (“Anritsu”), model number/options, serial number, and firmware package number, as shown in the example below.

> NI VISA Interactive Control USB Basic I/O Tab

> Note | When sending SCPI commands over Ethernet, it is required to send a newline termination character at the end of each command. In the example above, a newline character ("\n" in this case, but could be different depending on your programming environment) was used to terminate the *IDN? command.

> Note | When sending query commands over raw socket, the entire buffer must be read before the next query command is sent. Each query result is terminated by a newline to help identify the end of the query response. Query read operations could be broken into multiple reads, if necessary.

> Note | When using raw socket connections, you must close a session before opening a new one or before switching to a new protocol (such as USB). If you try to open a new session or switch protocols without first closing the previously opened session, you may lose communications with the instrument and not be able to reconnect until you reboot the instrument.