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Chapter 3
Before operating the AG-Star for the first time, ensure that you have followed the installation instructions in
Chapter 2, Installation and Setup on page 13. It is assumed that a computer is used during initial operation
and testing for greater ease and versatility.
3.1
Communications with the Receiver
Communication with the receiver typically consists of issuing commands through the communication ports
from an external serial communications device. This could be either a terminal or computer that is directly
connected to the receiver serial port using a DB-9 connector on the AG-Star multi-cable. If you are using a
radio, it connects to another DB-9 connector on the same multi-cable by means of the radio serial cable
supplied with the radio. It is recommended that you become thoroughly familiar with the commands and logs
detailed in the
OEMStar Firmware Reference Manual
capabilities.
When power is applied to the AG-Star, the Power LED lights and the AG-Star begins a self test
and the boot up process. After the self test and boot up have completed, the command prompt
becomes available on the serial port.
3.1.1
Serial Port Default Settings
The receiver communicates with your computer or terminal via an RS-232 serial port. For communication to
occur, both the receiver and the computer or terminal have to be configured properly. The receiver's COM1
and COM2 default port settings are as follows:
•
9600 bps, no parity, 8 data bits, 1 stop bit, no handshaking, echo off
Changing the default settings requires using the COM command. See Section B.2, COM Configure COM
Port on page 51 for details.
The data transfer rate you choose determines how fast information is transmitted. For example, outputting 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 is lower and depends on the
number of satellites being tracked, data filters in use and idle time. It is suggested that you leave yourself a
margin when choosing a data rate (115200 is recommended for most applications).
Although the receiver can operate at data transfer rates as low as 300 bps, this is not desirable.
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 will overflow the serial port
buffers, causing an error condition in the receiver status and loss of data.
3.1.2
Communicating Using a Remote Terminal
One method of communicating with the receiver is through a remote terminal. The receiver is pre-wired to
allow proper RS-232 interface with a data terminal. To communicate with the terminal, the receiver only
requires the RX, TX and GND lines to be used. Request to Send (RTS)/ Clear to Send (CTS) hardware
handshaking is not available. Ensure the terminal's communications set-up matches the receiver's RS-232
protocol.
AG-Star User Manual Rev 4
Operation
to ensure maximum utilization of the receiver's
20
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