relay.py

import time
import os
import sys
import dronekit
from dronekit import connect, VehicleMode
import socket
import exceptions



###Initialization process
##
##Print PID to tempfile
#
print("Writing relay.py PID to tempfile")
try:
    with open("/tmp/relay.py.pid", "w") as temp_file:
        temp_file.write(str(os.getpid()))
except:
    print("PID could not be written.\nThis feature will not work in Windows.")

##Set-up logging
#
print('Starting logfile')
am_logging = True
log_file = None
try:
    log_file = open("/tmp/relay.py." + str(time.time()) + ".log", "w")
    print("Opened log file")
except:
    #log file not working
    am_logging = False
    print("Log file couldn't be opened.\nThis feature will not work in Windows.")

#Write to a logfile
def log_line(text):
    print(str(text))
    if am_logging:
        log_file.write(str(text) + "\n")


# Connect to the Vehicle.
connection_string = 'udp:127.0.0.1:14550'

log_line("Connecting to vehicle on: %s" % (connection_string,))
vehicle = None #connect(connection_string, wait_ready=True)

try:
    vehicle = dronekit.connect(connection_string, wait_ready=True, baud=57600)
    log_line("Success!")

# Bad TCP connection
except socket.error:
    log_line('No server exists!')

# Bad TTY connection
except exceptions.OSError as e:
    log_line('No serial exists!')

# API Error
except dronekit.APIException:
    log_line('Timeout!')

# Other error
except:
    print(str(sys.exc_info()))
    log_line('Unknown error while trying to connect!')

# Get some vehicle attributes (state)
log_line("Vehicle attribute values:")
log_line(" GPS: %s" % vehicle.gps_0)
log_line(" Battery: %s" % vehicle.battery)
log_line(" Last Heartbeat: %s" % vehicle.last_heartbeat)
log_line(" Is Armable?: %s" % vehicle.is_armable)
log_line(" System status: %s" % vehicle.system_status.state)
log_line(" Mode: %s" % vehicle.mode.name)    # settable

#Finished
log_line('Initialized!')

# Close vehicle object before exiting script
vehicle.close()

# Done
print("Completed")