51
Remote Control
ses can be preset. A DHCP server is usually already inte-
grated in a router (DSL router, ISDN router, Modem router,
WLAN router, …) integrated. If a network element (e.g. an
instrument) is connected by a network cable directly with a
host (PC), the IP addresses cannot be assigned to the ins-
trument and the host (PC) automatically, since no network
with DHCP server is present here. They have to be preset
therefore at the instrument and at the host (PC) manually.
IP addresses are divided by using subnet mask into a
network quota and into a host quota, so similarly e.g. a
telephone number is divided in pre selection (land and local
area network number) and call number (user number).
Subnet mask have the same form as IP addresses. They
are represented with four decimal numbers separated
by points (e.g. 255.255.255.0). As is the case for the IP
addresses here each decimal number represents a binary
number of 8 bits. The separation between network quota
and host quota is determined by the subnet mask within
an IP address (e.g. the IP address 192.168.10.10 by the
subnet mask 255.255.255.0 is divided into a network quota
192.168.10.0 and a host quota of 0.0.0.10). The allocation
takes place via the transformation of the IP address and
the subnet mask in binary form and afterwards a bit by bit
one logical AND operation between IP address and subnet
mask. The result is the network quota of the IP address.
The host quota of the IP address takes place via the bit by
bit logical NAND operation between IP address and subnet
mask. By the variable allocation of IP addresses in network
quota and host quota via subnet masks, one can specify IP
address ranges individually for large and small networks.
Thus one can operate large and small IP networks and
connect if necessary to the Internet via a router. In smaller
local networks the subnet mask 255.255.255.0 is mostly
used. Network quota (the first 3 numbers) and host quota
(the last number) are simple here without much mathe-
matical expenditure to determine and it can with these
subnet mask up to 254 network elements (e.g. measuring
instruments, hosts/PC‘s...) in a network be operated at the
same time.
Often also a standard gateway is present in a network. In
most local networks is this gateway with the router to the
Internet (DSL router, ISDN router etc.) is identical. Using
this (gateway -) router a connection can be manufactured
with another network. Thus also network elements, which
are not in the same (local) network, can be reached and/
or network elements from the local network are able to ex-
change data with network elements from other networks.
For a network-spreading data exchange the IP address of
the standard gateway must also be preset. In local net-
works, mostly the first IP address within a network for this
(gateway -) router is used. Mostly routers in a local network
to be used as gateway have an IP address with a „1“ in the
last place of the IP address (e.g. 192.168.10.1).
9.3.2 Ethernet settings
In addition to the USB interface, the interface card includes
an Ethernet interface. Select Ethernet as interface and
press the soft menu key PARAMETER to then determine
the settings for the necessary parameters directly within
the ¸HMC8012. You can specify all parameters and
assign a fixed IP address. You can also assign a dynamic IP
address with the activated DHCP function. Please contact
your IT management to configure the settings properly.
If the device has an IP address, it can be accessed via web
browser at this IP since the Ethernet interface includes an
integrated web server. Enter the IP address in the browser’s
address bar (http://xxx.xxx.xxx.xxx). This will open a win-
dow including the instrument type and the serial number.
9.3.3 LXI
LAN eXtensions for Instrumentation (LXI) is an instrumen-
tation platform for measuring instruments and test systems
that is based on standard Ethernet technology. LXI is Ope-
ration in a Network intended to be the LAN-based succes-
sor to GPIB, combining the advantages of Ethernet
with the simplicity and familiarity of GPIB.
The ¸HMC8012 is LXI certified and supports the ver-
sion 1.4 (LXI Core 2011). Advanced functions are not sup-
ported. IVI (Interchangeable Virtual Instrument) instrument
drivers are a central component for the LXI certification. So
called IVI.net drivers are made available that are based on
PC and instrument have to be connected to the same network.
Otherwise a remote connection is not possible.
Fig. 9.10: Ethernet settings
If DHCP is used and the system cannot assign an IP address to the
¸HMC8012 (for instance, if no Ethernet cable is connected or
the network does not support DHCP), it may take up to three min-
utes until a timeout allows the interface to be configured again.
