Troubleshooting guide

option. If this option is not correctly set up then you will not be able talk to the logger at all, so accurate
configuration is vital.
It is really important to appreciate that the USB logger can run in two distinct modes which are termed
‘serial’ (or VCP) and USBXpress. (Yes, even though the logger has a USB connection, one of its operational
modes is called ‘serial’.) Understanding the logger modes is actually quite easy, but does take a number of
words to explain – please read the notes below with care.
Software can only talk to the logger if the software also utilises the same communications mode to which the
logger is currently set, ie serial or USBXpress. If a software program tries to talk to the logger in the ‘wrong’
mode then it will not receive a response and it will appear that communications between logger and
computer are broken. More details about diagnosing the current logger mode will be found in the Comms
troubleshooting topic, but here is a brief summary of how the logger mode is used:
The USBXpress mode is called simply ‘USB’ for short and the serial or VCP (Virtual Comm Port) mode is
termed ‘serial’. In the ‘serial’ mode the logger behaves as if it were a standard RS232 serial device, despite
the physical connection being USB in nature. This means that data is received by PC software as if it were
being received on a numbered comm port (COM1, COM2 etc) except of course that the COM port is an
imaginary or virtual one rather than a real physical COM port. The key point is that if software is configured
to expect data on a serial COM port then the correct COM port number must be set in the software (unless
the software is clever enough to auto-detect the logger’s COM port number, which can work well but is not
always infallible).
In summary, if the logger is set to USB mode then software must also be set to expect data in USB mode.
And conversely if serial mode is set on the logger then software must be configured to look for incoming
data on a serial port with the correct COM port number. The logger remembers which mode it is set to even
when powered off, hence the possibility of a mismatch between logger mode and what the software is
expecting, especially if new software is being evaluated.
Three other key points:
• There is no practical difference between USB and serial modes – the two are directly equivalent and
one is no faster nor more accurate than the other;
• At present the only software that can use USB mode is the Davis Weatherlink software. If you’re
planning only to use the Weatherlink software then USB mode is the simplest to set up.(because it
can be configured automatically and does not require the user to identify which COM port number to
set). But no other software currently seems able to use USB mode and so, if you’re planning to use
any other software than Weatherlink be sure to select serial mode and NOT USB mode.
Prodata Weather Systems Davis Weather Stations KB - Prodata Weather Systems - 1
Generated by Manula.com on: 2015/05/16 15:14:01 Page 36 of 73