The 1.0.20 version of SimpleDigitalLocomotive for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free Mac application was originally created by Manfred and Christian Fischer. SimpleDigitalLocomotive for Mac lies within Lifestyle Tools, more precisely General.
From the developer:
SimpleDigitalLocomotive is intended to control digital model railway locomotives and function models via the serial port (RS.422 (or RS.232 via USB)) or Ethernet port of an Apple Mac running OS X 10.3.9 / 10.4.11 / 10.5.2 / 10.6.1 / 10.7.0 /10.8.2 or newer. It can control digital model railway locomotives, function models and accessories via serial ports on a Mac.
Supported digital central units: M