Novatel SMART-AG user manual Chapter Operation, Communications with the Receiver

Chapter 3

Operation

Before operating the SMART-AG for the first time, please ensure that you have followed the installation instructions in Chapter 2, Installation and Setup starting on Page 20. The following instructions are based on a COM port configuration such as that shown in Figure 5 on Page 30. It is assumed that a personal computer, or laptop, is used during initial operation and testing for greater ease and versatility.

3.1Communications 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 PC/laptop that is directly connected to the receiver serial port using a DB-9 connector on the SMART-AG mult- 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 OEMV Firmware Reference Manual to ensure maximum utilization of the receiver’s capabilities.

3.1.1Serial Port Default Settings

The receiver communicates with your PC/laptop 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 COM1and 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.

The data transfer rate you choose 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. Please 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 therefore suggested that you leave yourself a margin when choosing a data rate (115200 is recommended for most applications).

CAUTION: 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, cause an error condition in the receiver status and result in lost data.

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