possible to edit firmware not replace it?

I am using a RAMPS 1.4 board and would like to store the existing firmware before I tamper with it (as in, replace it). The 3d printer I am using has been obtained second hand and I do not have the files, I would be loath to introduce problems to a printer that is mostly functioning well. Is it possible to download existing firmware from the board?

If it is Marlin... You can do a M503 and print out most of the important settings. Anything that isn't printed out, is going to be obvious the first time you load the firmware and it doesn't work exactly the same.

For example, if one of the axis is inverted, you will see it move the wrong way and be able to flip it.

But with that said... We should add an instruction to hex dump the current firmware to save it. (But the AVRDude program will dump it too if you want to save it.)

Don't sweat it. If you the new firmware doesn't work exactly correct... You will have plenty of help to get the one or two settings back to the way they should be.

Ignore this post. It went to the wrong thread...

Edited 1 time(s). Last edit at 12/30/2015 10:54PM by Roxy.

Depending on what isn't working well, you can get around flashing a new firmware by changing parameters with "Mxxx" commands.
Maybe the problems aren't in firmware but in slicer settings?
-Olaf

If I load prontrface and issue a M105 it reads the temperature on T0 and lists zero for the others.

You have to re flash the firmware for this, and set the thermistors types for T1 and T2, by default its set to type 0, ie off.

It is really strange why it was decided to no be able to download.

Modern firmwares such as RepRapFirmware and Smoothieware allow you to change all the parameters including thermistor types using a configuration file on the SD card. Older firmwares such as Marlin don't provide this facility.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].