I am unable to compile the code for the raspberry pi 2 so that I may test with this unit.

admin@raspberrypi:/RS485_Wind_Speed_Transmitter $ sudo gcc -Wall -lwiringPi -o Wind_Speed *.c
/usr/bin/ld: /tmp/ccfI7bSF.o:(.bss+0x0): multiple definition of `fd'; /tmp/cc3JNLfF.o:(.bss+0x0): first defined here
/usr/bin/ld: /tmp/cc3JNLfF.o: in function `main':
main.c:(.text+0x24): undefined reference to `delay'
/usr/bin/ld: main.c:(.text+0x88): undefined reference to `delay'
/usr/bin/ld: /tmp/ccfI7bSF.o: in function `ModifyAddress':
RS485_Wind_Speed_Transmitter.c:(.text+0x158): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x1b0): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x1c8): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x1f8): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x210): undefined reference to `serialDataAvail'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x224): undefined reference to `delay'
/usr/bin/ld: /tmp/ccfI7bSF.o: in function `Init':
RS485_Wind_Speed_Transmitter.c:(.text+0x3b8): undefined reference to `serialOpen'
/usr/bin/ld: /tmp/ccfI7bSF.o: in function `readWindSpeed':
RS485_Wind_Speed_Transmitter.c:(.text+0x478): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x4c8): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x4ec): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x51c): undefined reference to `millis'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x534): undefined reference to `serialDataAvail'
/usr/bin/ld: RS485_Wind_Speed_Transmitter.c:(.text+0x548): undefined reference to `delay'
collect2: error: ld returned 1 exit status

Can anyone assist?