Chapter 3 OEM7 Receiver Operation
OEM7 Installation and Operation User Manual v4
50
A computer has several USB ports. The assignment of COM port numbers is tied to a
USB port on the computer. This allows receivers to be switched without Microsoft Win-
dows assigning new COM ports. However, if the receiver is connected to a different phys-
ical USB port, Windows detects the receiver's presence and assigns three new COM port
numbers.
3.1.2 Serial Port Communications
The receiver can communicate with a computer or terminal via a serial port. For communication
to occur, both the receiver and the operator interface have to be configured properly. The
receiver’s default port settings are:
l
9600 bps
l
no parity
l
8 data bits
l
1 stop bit
l
no handshaking
l
echo off
l
break on
The data transfer rate determines how fast information is transmitted. Take for example a log
whose message byte count is 96. The default port settings allows 10 bits/byte (8 data bits + 1
stop bit + 1 framing bit). It therefore takes 960 bits per message. To get 10 messages per
second then requires 9600 bps. Also remember that even if you set the bps to 9600, the actual
data transfer rate may be lower and depends on the number of satellites being tracked, data fil-
ters in use, and idle time. It is therefore suggested that you leave yourself a margin when choos-
ing a data rate.
The minimum suggested baud rate for most applications is 115200 bps for GNSS only or
230400 bps for GNSS+INS. If the buffer overrun flag is present in the
RXSTATUS
log
(refer to the
OEM7 Commands and Logs Reference Manual
), log at a higher baud rate if
possible, or change to a medium supporting higher bandwidth (USB or Ethernet).
Although the receiver can operate at data transfer rates as low as 300 bps, this is not
recommended. For example, if several data logs are active (that is, a significant amount
of information needs to be transmitted every second) but the bit rate is set too low, data
overflows the serial port buffers, causing an error condition in the receiver status that
results in lost data.
Refer to
on page 40 for additional default setting details.
The following ports are supported and can be configured using the commands listed. Refer to the
commands listed in the
OEM7 Commands and Logs Reference Manual
for detailed instructions.
