I use Red Lion HMIs, the good news is that the software is very flexible and a free download, the bad news is that Strings aren't part of the Siemens driver. You can still read/write and display strings, but you have to do some fiddling on string lengths to get it to be right on screen. https://www.redlion.net/products/industrial-automation/hmis-and-panel-meters/hmi-operator-panels