BNC 845-M - Manual (Page 7)

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Model 845-M Programmer’s Manual V1.1 2011
VISA is an IO library used to develop IO applications and instrument drivers that comply with industry
standards. It is recommended that the VISA library be used for programming the signal generator. The NI-VISA
and Agilent VISA libraries are similar implementations of VISA and have the same commands, syntax, and
functions.
Using Telnet LAN
Telnet provides a means of communicating with the signal generator over the LAN. The Telnet client, run on
a LAN connected computer, will create a login session on the signal generator. A connection, established
between computer and signal generator, generates a user interface display screen with “>” prompts on the
command line.
Using the Telnet protocol to send commands to the signal generator is similar to communicating with the
signal generator over LAN. You establish a connection with the signal generator and then send or receive
information using predefined commands. Communication is interactive: one command at a time. The telnet
service is available on port 18.
Once a telnet session to the device is established, the echo can be enabled by typing
SYST:COMM:SOCK:ECHO ON
Following this command a prompt “>>” should become visible.
USB (fully supported from Firmware 0.4.0 upwards)
The Model 845-M supports the following USB interface protocols:
1) USBTMC class device via VISA
2) USBTMC: the application programming interface (API) provided with the instrument supports
general programming using the USB interface under Windows operating system.
USB-TMC Interface Connection and Setup using VISA
USBTMC stands for USB Test & Measurement Class. USBTMC is a protocol built on top of USB that allows GPIB-
like communication with USB devices. From the user's point of view, the USB device behaves just like a GPIB
device. For example, you can use VISA Write to send the *IDN? query and use VISA Read to get the response.
The USBTMC protocol supports service request, triggers and other GPIB specific operations.
USBTMC upgrades the physical layer from GPIB to USB while maintaining software compatibility with existing
software, such as instrument drivers and any application that uses VISA. This is also what the VXI-11 protocol
provides for TCP/IP.