SiCalc

Calculator for PLC programmers, it can be useful for any kind of PLC but it especially developed for Siemens S7 Series programmers.

It shows DEC, BIN and HEX values together and you can use any of them to enter values.
It also show representation and valid data types for entered value.
You can swap values Big Endian to Little Endiand and vice verse.
It also supports Binary functions such as AND, OR and Shifting.