F1 like 3DOF Simulator with heave

I've tried that before, cause as soon as I put a cable from PIN8 to GND on the Arduino Uno, SMC3Utils won't beable to open up a communication "Could not establish comms with Arduino SMC3, Abort, Retry, Ignore".
Thats weird, cause the Sabertooth is set to 115200 baud with DEScribe.

I'm using SPS 8.2 softstart from this tutorial.

The code says:

Code:

    // set the data rate for the SoftwareSerial port
#ifdef SECOND_SERIAL
    mySerial.begin(115200);
#endif
#ifdef MODE3
{
  pinMode(8, INPUT_PULLUP);
  pinMode(9, INPUT_PULLUP);
  pinMode(10, INPUT_PULLUP);
  pinMode(11, INPUT_PULLUP);
  pinMode(12, INPUT_PULLUP);
 
  if (digitalRead(8) == HIGH){
    Serial.begin(500000);
  }
else
{
  Serial.begin(115200);
}
  if (digitalRead(9) == LOW){
    mySerial.begin(19200);
    ST[0].setBaudRate(115200);
    ST[1].setBaudRate(115200);
    mySerial.end();
  }
  else if (digitalRead(10) == LOW){
    mySerial.begin(38400);
    ST[0].setBaudRate(115200);
    ST[1].setBaudRate(115200);
    mySerial.end();
  }
  else
  {
    mySerial.begin(9600);
    ST[0].setBaudRate(115200);
    ST[1].setBaudRate(115200);
    mySerial.end();
  }
 
   mySerial.begin(115200);

So yes, I would expect, jumpering PIN 8 and GND, the Arduino would be set to 115200 and otherwise run with 500000 Baud.
I think I'll open up the Arduino IDE and try to see if the console using 115200/500000 baud shows something useful.

Ok, so I could prove that jumpering PIN 8 and GND leads to the Baud rate getting set to 115200.
Testet it with a simple Outut to the Serial Monitor in Arduini IDE. 115200 was readable, 500000 not.

The Code works, but still, SMC3Utils won't connect with a Baud rate set to 115200 but only with a Baud rate of 500000.
Do I need to use another version of SMC3Utils? I'm using version 1.01 of the mentioned thread.