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Remote Control
9 Remote Control
By default, the ¸HMC8012 includes an Ethernet and a
USB interface
In addition to a LAN interface, the ¸HMC8012 includes
a USB device port. For this interface, the user can select
if the instrument is accessed via virtual COM port (VCP)
or via USB TMC class. The ¸HMC8012 is option-
ally available ex factory with an integrated GPIB interface
(¸HMC8012-G). The GPIB interface has its own inter-
face slot on the rear panel.
9.1 USB VCP
The traditional version of the VCP (virtual COM port) allows
the user to communicate with the HMC using any termi-
nal program via SCPI commands once the corresponding
Windows drivers have been installed. These commands
are generally compatible with the Agilent multimeters
34401A and 34410A. The actual USB-VCP driver can be
downloaded from the Rohde & Schwarz homepage for
free. If a connection between PC and the instrument has
been established and no HMC USB-VCP driver is installed,
the operating system answers with “Found New Hard-
To enable communication, the selected interface and the respec-
tive settings in the instrument must be identical to the selections
for the PC.
Fig. 9.1: Rear panel
All currently available USB VCP drivers have been fully tested and
released for Windows XP™, VISTA™, Windows 7™ and Windows
8™ (32 + 64 Bit).
Fig. 9.2: USB VCP setting
ware”. In addition, the “Found New Hardware Wizard” is
displayed. Only in this case the USB-VCP driver must be
installed. Further information about the USB-VCP driver ins-
tallation you can find in the installation guide internal of the
driver file. In addition, you may use the free software “HM-
Explorer”. This Windows application offers ¸HMC8012
instruments a terminal function and the option to create
screenshots.
9.2 USB TMC
A modern alternative to the virtual COM port (VCP) is the
control via USB TMC class. TMC stands for „Test & Mea-
surement Class“ which indicates that the connected mea-
surement instrument can be recognized without special
Windows drivers if VISA drivers are installed and that it
can be used directly in corresponding environments. The
GPIB interface serves as model to the structure of the
TMC design. A major benefit of the USB TMC class is that
by sampling specific registers the user can determine if
commands have been terminated and if they have been
processed correctly. However, the communication via VCP
requires analysis and polling mechanisms within the cont-
rolling software which may significantly strain the interface
of the measurement instruments. The TMC status registers
solve this problem with the USB TMC in the same manner
as is the case with the GPIB interface for the hardware,
namely via corresponding control lines.
9.2.1 USB TMC Configuration
The ¸HMC8012 require a generic USB instrument
driver to be operated in USB-TMC mode. The USB Test &
Measurement class (USB-TMC) is a protocol that enables
GPIB-like communication via USB interfaces and a sepa-
rate instrument class of the USB specification. The USB-
TMC protocol supports service requests, trigger and other
GPIB-specific commands. The driver is included in the
NI-VISA package (Virtual Instrument Software Architecture)
and can be downloaded at http://www.ni.com/downloads/
ni-drivers/.
You need to first install the NI-VISA drivers on your Win-
dows system. Please download the most recent version
of the NI-VISA driver package. Extract the previously
downloaded driver package and follow the installation
instructions.
The following requirement for USB-VCP driver installation are
necessary:
1 ¸HMC8012 with an activated USB-VCP interface.
2 A PC with operating system Windows XP, VISTA, Windows 7 or
Windows 8 (32 or 64Bit).
3 Administrator rights are necessary for the installation of the
driver. If an error message regarding spelling errors appears,
the rights to install the driver are not given. In this case, please
contact your IT department to obtain the necessary rights.
The HMExplorer software does not support the communication via
USB TMC.
