Campbell Scientific SC-USB USB to CS I/O Optically Isolated Interface - Manual (Page 34)

SC-USB USB to CS I/O Opto-isolated Interface
28
these cases the SC-USB needs to be set to a fixed baud rate. This can either be
done using the SC-USB utility program (see Section 3.2) or if your software
package supports it; for example by using the ‘Generic modem’ option of
LoggerNet, the baud rate can be set by sending a single character code at the
start of each call to the datalogger. The codes are shown in the table below.
ASCII
Character
Baud Rate
1 9600
2 38400
3 57600
4 115200
5 76800
6 115200
The SC-USB can be left in auto mode; the numeric characters will not be
echoed.
If using the generic modem option of LoggerNet, you would enter a generic
modem between the COM port and the datalogger, and enter T"1" in the dial
script to force the baud rate to 9600 baud; the other hardware settings can be
left at their default values.
Setting the baud rate using the latter method is useful if you use the SC-USB to
move between a number of different types of dataloggers and wish to avoid
having to reconfigure it too often.
If you experience any problems using this software, please report this to
Campbell Scientific, giving full details with any solution if available, for
possible inclusion in a future release of this User Guide.
5.3 Electronic Interference
Electronic emissions emanating from the SC-USB interface itself are very low.
However, while verifying this during the development of the SC-USB,
Campbell Scientific became aware that many PCs have poor filtering of
emissions from their USB ports.
These emissions become apparent when a cable is plugged into the USB port,
as the cable acts as an antenna. If any such PC emissions (coming from the
SC-USB cable) cause problems with other equipment, you may be able to
reduce such noise by adding a clip-on ferrite choke to the SC-USB cable.
Position the choke on the cable close to the USB connector. The size of ferrite
is dependent on the level and frequency of noise emitted by the PC, and so
needs to be selected by trial and error. If in doubt, seek advice from the PC
manufacturer.