BotronikS - Final code for all types of Arduino and PC users: -- HOME -- email:
What you need to install or have installed before on your PC: see HERE

BAC16out: Status control of up to 16 Arduino outputs by AT commands (from PC, PLC...)

connections (click to enlarge)

XLoader exsample

Termite test...

Useful accessories:  
SSR module:
All offered codes here are FREE to use! Source codes and Your special requests are available via email!
Download the HEX codes below, unpack and upload to the proper Arduino board (Use a free net tool for example XLoader)
1. ATmega328-16MHz (MINI,NANO,UNO...): Hex-m328
2. AtMega2560 (Mega(ATMEGA2560)........): Hex-m2560
Based on the offered AT commands, you can develop your own PC, PLC ... communication code, and applications...
Available AT commands (Baud 9600,8 Data bits, None Parity,1 Stop Bit): You can test the uploaded code using some free serial software such as Termite Termite (select: Append CR):
AT - attention command (return OK)
ATI - code info
? - reading the status of all outputs
A...P - set single OUTx at HI(5V) level (capital letters from A to P) - example: A
a...p - set single OUTx at LO(0V) level (small letter from a to p) - example: a
1 - Set all outputs at a high (5V) level
0 - set all outputs at low (0V) level

PC Application(s) for offered Hex code (for WINDOWS):
In order for the offered PC applications to work, it is necessary to download and install on PC (if no instaled - one time only) VB6RunTimePlus2.2
Download the offered app for PC, unzip it (let Windows do it and turn off all the bans it mentions), connect the hardware to the USB PC (find
the new automatically created COM port number in PC Device Manager), run the app and enter that number to the application.
NOTE: without connected hardware (with appropriate code) and PC communication with it - the PC application cannot continue!

Download PcApp: Here or click on image. Some user HELP is in app. Test the rest in use.