Hi Mike,
> I do agree that I probably need to do the operations sequentially but it does not look like the Keyword command has the wait parameter as some of the other commands do.
Well, actually I was refering to the DOS (well, command shell) "Start /wait" command there. You could use it in your batchfile to call tpcmd, so that the shell would wait until tpcmd has terminated before it processes the next command. So, in your batchfile, you'd use "Start /wait tpcmd.exe" instead of just "tpcmd.exe".
> Thanks for the tip about ExifTool - if I use that and assign the keywords directly to the image does ThumsPlus pick those up when you add the image?
Yes, if you have configured TP to copy metadata (IPTC keywords) to the database when it creates thumbnails, that's what it will do. ExifTool has been around for a very long time and from what I hear it's very versatile and reliable (as well as somewhat complicated :).
> The other potential issue is that I use SQL Server 2012 as my Pics DB so maybe the DDE commands are actually being rejected or not handled by SQL Server correctly.
Well, theoratically at least there should be no difference between how TP works with the database, whether you issue commands to it through DDE (as tpcmd does) or from the menu or keyboard.
> I'm thinking the best alternative is just to insert or update the keywords in the database directly via C# and SQL commands.
That's an option too, but then you'll have the keywords stored only in the database and not in the image files. It's generally best to have them in both, just so you'll always have access to the keywords as long as you have the images.
BTW, do you happen to still have a copy of ThumbsPlus 7 on your system? It's probably a stupid thought, but I'm wondering if tpcmd.exe might be running that instead of TP10.