GPS for Dummies.pdf - Engineering Surveyor

158Part III: Digital Mapping on Your Computer Parity: This is a form of error checking that ensures the integrity oftransferred data. Stop bits: This is how many bits follow a character and mark the end ofa data transmission. Flow control: Sometimes called handshaking, this is a way for onedevice to stop another device from sending data until it’s ready toreceive the data.Although you can set COM properties in Device Manager, I recommendmaking changes in the program that you’re using to interface with the GPSreceiver. You’ll usually see an Options or Configuration menu in the programthat displays a dialog box where you can set these values. (See Figure 9-2 foran example of a communications setting dialog box in a mapping program.)Figure 9-2:Set COMpropertiesto matchyourinterfaceprogram.Unless the program specifies otherwise, here are the typical COM port settingsto use when interfacing with a GPS receiver: Baud rate: 4,800 and 9,600 baud are almost certainly guaranteed to workwith all GPS receivers. You can increase the speed to a higher rate onsome types of GPS receivers. The higher the speed, the faster the datatransfer. I recommend experimenting until you find the fastest, mostreliablebaud rate, and then using that setting. Data bits: 8. Parity: None. Stop bits: 1. Flow control: None.