I believe you are using an Arduino MEGA, correct? If so, my ST_Anything library utilizes one of the MEGA’s additional Hardware Serial ports on pins 14 & 15 as mentioned in the main ReadMe for ST_Anything at github. Using Hardware Serial offers better performance and is more reliable than using Software Serial. Also, this is why you must use the version of the SmartThings library from my GitHub repository. It has added support for the Arduino MEGA whereas the version from ST does not. We also made several optimizations to reduce memory usage and improve performance.
From the ReadMe…
•If using an Arduino MEGA, Hardware Serial is used on pins 14/15 (add jumpers from Pin14 to Pin2 and another from Pin15 to Pin3)
You’ll want to keep the small switch on the ThingShield set to pins2/3. Just do not try using pins 2 & 3 for anything else. Pins 0, 1, 2, 3, and 6 are essentially reserved for use by the ThingShield.
So, just wire pin 14 to pin 2, and wire pin 15 to pin 3. With nothing else wired, that should be enough to get the Arduino talking to ST.
If you connect a pushbutton between GND and pin 38, pressing it will turn on Relay 1. Pressing it again will turn relay 1 off.
Note: in the serial debug window of the Arduino, you will see the “relays” called “switch1”, “switch2”, etc… This is because they are supporting the “Switch” capability of the SmartThings world. This is the same ST Capability that is supported by any device that can be turned on/off, like a light switch, wall outlet, lightbulb, etc… The Arduino’s digital outputs are "switch"ing the connected relays on and off.
Hopefully this gets you started… Happy to help if you run into any other issues.