Çok teşekkür ederim. Yardımınız için.Sadece .h ve .ccp değil bütün klasörü atınca gördü. Bu sefer de aşağıdaki hataları verdi.
Arduino:1.7.11 (Windows 7), Kart:"Arduino Uno"
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp: In function 'void waiting_for_reply()':
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp:224:6: error: 'Serial3' was not declared in this scope
if (Serial3.available()) // is there something to check?
^
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp: In function 'void modbus_configure(long int, unsigned char, unsigned int, unsigned int, unsigned char, unsigned char, Packet*, unsigned int)':
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp:463:2: error: 'Serial3' was not declared in this scope
Serial3.begin(baud, byteFormat);
^
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp: In function 'void sendPacket(unsigned char)':
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp:518:4: error: 'Serial3' was not declared in this scope
{Serial3.write(frame);
^
C:\Program Files (x86)\Arduino\libraries\SimpleModbusMasterAET\SimpleModbusMasterAET.cpp:525:2: error: 'Serial3' was not declared in this scope
Serial3.flush();