Rohde & Schwarz NRP TWG Series, User Manual

Page: 100 / 128

Remote Control Basics
R&S
®
NRPxxTWG
100 User Manual 1178.8371.02 ─ 04
9 Remote Control Basics
● Remote Control Interfaces and Protocols ............................................................. 100
● SCPI Command Structure .....................................................................................101
● Status Reporting System ...................................................................................... 107
9.1 Remote Control Interfaces and Protocols
For remote control, communication between the R&S NRPxxTWG power sensors and
the controlling host is established based on various interfaces and protocols.
Depending on the sensor type, the power sensors support different interfaces for
remote control.
●
R&S NRPxxTWG power sensors are always accessed using USB.
Table 9-1 describes the protocols that are supported for each interface.
Table 9-1: Remote control interfaces and protocols
Interface Supported by
Protocols, VISA
*)
address string and Library
USB All
power
sensors
●
USBTMC
USB::<vendor ID>::<product ID>::<serial number>[::INSTR]
VISA
●
NRP legacy protocol
(
*
) VISA is a standardized software interface library providing input and output functions to communicate with instruments. A VISA
installation on the controller is a prerequisite for remote control over USBTMC and LAN (when using VXI-11 or HiSLIP protocol)
interfaces.
9.1.1 USB Interface
For remote control using USB connection, the computer and the power sensors must
be connected via the USB interface. A USB connection requires the VISA library to be
installed. VISA detects and configures the R&S power sensors automatically when the
USB connection is established. Apart from the USBTMC driver (which comes with the
installation of the R&S NRP Toolkit), you do not have to install a separate driver.
USB Test & Measurement Class Specification (USBTMC) is a protocol that is built on
top of USB for communication with USB devices. It defines class code information of
the sensor, that identifies its functionality to load the respective device driver. Using
VISA library, it supports service request, triggers and other operations that are com-
monly found in GPIB devices.
Besides USBTMC, the NRP legacy protocol is available to ensure the compatibility of
the R&S NRPxxTWG power sensors with the R&S
NRP
‑
Z series of power sensors.
The usage of this protocol is not recommended for new applications.
The resource string represents an addressing scheme that is used to establish a com-
munication session with the sensor. It is based on the sensor address and some instru-
ment- and vendor-specific information.
Remote Control Interfaces and Protocols