I need to calculate a checksum byte for NEC LCD monitor strings. It's an XOR of most of the bytes in a single hex string. Each string I need (just power and inputs) is fairly long, and though I could do this manually using a calculator, that's tedious and error prone enough to make me look for an automatic solution.

I found this thread about creating an Excel Visual Basic module:
[Link: mrexcel.com]
but I can't get it to compile, even though I've installed the analysis add-in and gone into tools->references and ticked atpvbaen.xls.

I've also heard of a simple checksum calculator available from RTI, but I've not come across it yet.

Can anyone help out with this?

I can't help, but I think that google probably can:

[Link: lmgtfy.com]

I would imagine that one of the search results in the above list will work for you.

The time you've spent writing VB and searching could have been spent using Windows Calculator and you'd be done by now.

This won't be the last time I need to calculate a bunch of XOR checksums. Also I didn't write that module.