Picked up a used UP700 from a fast food store that went under. Should I do a master reset before trying to program it for use in the bar for our VFW Post? Can I hook this to a computer and put in descriptions and prices of items? Tried to hook up the ethernet cable and a serial cable but could not get it to communicate to the computer with the free version SLFv3 software from lynxsoft dot com. Am I missing something? Looking for help to steer me in the right direction. Thanks!

DON'T master reset unless you are very familiar with dealer programming. You will lose a LOT of dealer settings. Just edit the items in PGM2 mode/settings/Article/PLU.
You need to have a sharp serial cable. Make sure it is wired correctly for the software you are using. It will normally come with a diagram for making the cable, or buy one from sharp. The other techs may know the wiring for this software. i haven't used it.

Thanks for the tip. I'll make up another serial cable and give it another shot. Do you know if the ethernet port is active? Did notice that there is an empty slot in the rear of the machine, could that be for an eternet card or would that be for a memory expantion board?

Yes, there is an add on board inside for Ethernet so you can network machines together. Memory expansion is in the side of the machine.

Thanks for your help. Still can't connect to a computer via serial cable. When I run the diagnostics I get a com port failure. So I guess it's time to take it to a service center and let the pro's have at it.

No. That is normal because you don't have a loopback test connector in there while running diagnostics.
Make sure you have set the online port in device assign menu to the port number that you are using and there is a baud rate setting in online config menu. Set it to the highest baud using the decimal point I think. There is probably nothing wrong with the machine. If no one has set it up before, it won't be ready to communicate with the PC. See how you get on. I'm going from memory, so i can give you more specific instructions if you don't find the settings