Thanks for your answer.
I try to send from the USB-port from an iMac to Arduino Uno (from Kjell&Co) usb port. To the Arduino I have a ESP8266 wifi module connected, also tied with a IOT GA6 gsm/gprs module.
I am neon this with both programming and Arduino but try to learn...
The sketch-example below is one I have tested/struggled with but I have also the one that worked earlier with ESP8266 module.
I think I need to learn something basic 
#include <SoftwareSerial.h>
SoftwareSerial GPRS(7, 8);
unsigned char buffer[64]; // buffer array for data recieve over serial port
int count=0; // counter for buffer array
void setup()
{
GPRS.begin(9600); // the GPRS baud rate
Serial.begin(9600); // the Serial port of Arduino baud rate.
}
void loop()
{
if (GPRS.available()) // if date is comming from softwareserial port ==> data is comming from gprs shield
{
while(GPRS.available()) // reading data into char array
{
buffer[count++]=GPRS.read();
if(count == 64)break;
}
Serial.write(buffer,count); // if no data transmission ends, write buffer to hardware serial port
clearBufferArray(); // call clearBufferArray function to clear the storaged data from the array
count = 0; // set counter of while loop to zero
}
if (Serial.available()) // if data is available on hardwareserial port ==> data is comming from PC or notebook
GPRS.write(Serial.read()); // write it to the GPRS shield
}
void clearBufferArray() // function to clear buffer array
{
for (int i=0; i<count;i++)
{ buffer*=NULL;} *
}