Version 1.1 (released 14 April 2021)
http://razorbillinstruments.com
Page 17 of 40
M
P
2
4
0
:
H
IG
H
I
S
O
L
A
T
IO
N
M
U
LT
IP
L
E
X
E
R
connected to a laptop or similar portable computer, as these may
not provide a ground connection through the USB cable.
USB Serial communication
The MP240 multiplexer uses a USB virtual serial port to
communicate with a computer. The multiplexer acts as a bus-
powered USB2.0 full speed device, and requires up to 200 mA
from the computer or USB hub to which it is connected. Any
modern PC or powered USB hub will supply this level, but use
of unpowered hubs could lead to interruptions, depending on
what other devices are attached. You can also use standards-
compliant USB extenders. The standard allows for one “dumb”
5 m cable, and up to five “active” extenders or hubs, each adding
5 m of cable.
Microsoft Windows
Razorbill instruments supports the MP240 on Microsoft
Windows 7 and higher.
Before using your multiplexer, you should install the necessary
drivers for your operating system; these are available on the
Razorbill Instruments website. The Multiplexer may work with
windows built-in drivers, but our drivers have several advantages
including improved reliability of the USB link, and the correct
device name appearing in system menus.
When our drivers are installed and the multiplexer is plugged in,
a new serial port will appear on your system. Your operating
system will normally allow you to set baud rate, stop bits, parity
etc. for this port, but as there is no physical serial connection
within the multiplexer, these settings have no effect and should
be left at the defaults.
Once the virtual serial port has been created, it can be accessed
directly as a serial port, or indirectly using, e.g. VISA.
Whichever way it is used, you will also need either a terminal
