This info is mostly from the Meridian users group.
Base Map Backup
Here are the instructions on how to back up the base map in your Magellan Map 330 or better. All commands must be in ALL CAPITAL LETTERS.
Setup of the GPS
Delete memory.
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It might be easier to find the right file if you remove the SD card (if present).
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Connect the GPS to the PC.
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Switch the GPS on, make sure that the battery life indicator is over 50%, and turn off the NMEA output (Menu > Setup > NMEA > Off).
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Set the baud rate to the desired value (any value will do, but remember that the PC should be set at the same baud rate, see below). If too many errors occur, the baud rate can be reduced, but then it takes much more time to download (with 115200 bps it takes about 15 minutes).
Setup of the PC
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Start Hyperterminal: Start > Programs > Accessories > Communications > Hyperterminal.
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Make a new connection
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Connect Using: Direct to Com1 (or Com2, whatever Com port your GPS is connected to). Click OK.
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Port settings:
Bits per second: equal to GPS setting. I used 57,600
Data bits: 8
Parity: None
Stop bits: 1
Flow control: None
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On the advanced button you can adjust the receive and transmit buffer (putting both buffers on Low should be fine). Click OK.
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Now click the Disconnect icon to stop the communication between Hyperterminal and the GPS at this point. Click the Properties icon and choose the Setting Tab.
Keys act as: Windows-keys
backspace key sends: CTRL+H
Emulation: Autodetect
Telnet terminal: ANSII
Backscroll buffer lines: 500
Next, Click ASCII:
Check 'Send line ends with line feeds'
Check 'Echo typed characters locally'
Set both delays to 0 milliseconds
Check 'Append line feeds to incoming line ends'
Uncheck 'Force incoming data to 7-bit ASCII'
Check 'Wrap lines that exceed terminal width'
Click OK twice to close the two windows
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Now connect to the GPS (click on the Call icon) and type the following line into the window
$PMGNCMD,FIL,FIRST,*6B
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The unit will then respond with the name of the first file. This is usually the base map. On a Meridian with v4.02 firmware and the American Marine map v1.03, the response should be:
$PMGNFIL,FIRST,OK,1,BASEMAP.IMG,013124.00,09,05,102,10000,15406836*32
In the above example, the filename is “BASEMAP.IMG”.
On a Map 330 with the Australian Basemap the map file was called FIRSTMAP.DAT
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If you wish, you can enter in a line repeatedly to get an entire listing of the memory contents. This listing will include the contents of the SD card. The line to enter is:
$PMGNCMD,FIL,NEXT*1A
When you get a response of “$PMGNCMD,END*3D” then you have a listing of all files and there are no more to be displayed.
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The next step is to download the base map. If the basemap is called “BASEMAP.IMG”, then the line to enter is:
$PMGNCMD,FIL,DOWNLOAD,BASEMAP.IMG*01
If the basemap is NOT called BASEMAP.IMG, you will have to construct your own line, and compute the checksum (the checksum is the last field in the line; e.g. “01” in the example above. At the Magellan Meridian Yahoo Group (
http://groups.yahoo.com/group/Magellan_Meridian/files), you will find “Hex Checksum.zip”. Download this and follow the instructions in order to get the correct line checksum. You will need to join this group to download the app, however, if the file is called FIRSTMAP.DAT the required line is : $PMGNCMD,FIL,DOWNLOAD,FIRSTMAP.DAT*5C
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Go to Transfer > Receive File, and select the 1K Xmodem protocol. After that, name the basemap file that you will be receiving (I recommend using the same suffix as Magellan uses:.img)
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The file transfer should start now, and progress can be monitored (with a baud rate of 115200, it takes about 30 minutes), but I have found in noisy environments that a baud rate of 4800 may be required to get through without errors.
If you want to upload the basemap to your GPS you will need to use the firmware update software specific to your GPS from the Magellan site. This download includes the app Magup, and some critically important instructions. Be very careful, it is possible to crash your flash ram and destroy your GPS if you don't follow these to the letter!
To upload basemap only and leave firmware as is select expert mode and follow the prompts.
Bob