def create_rf_command_datagram(dest_callsign, dest_device_id, command,
payload):
"""
This function creates a command packet datagram for commanding REMOTE (RF) Faraday devices. This datagram encapsulates the actual command packets to the passed to the remote device as a payload.
The important difference between the RF and non RF command packet functions are remote callsign and ID arguments that tell Faraday what devices to target for commanding.
.. note:: Remote commanding simply calls a specific local command that transmits a "local" command packet as a payload to the target Faraday device. Also, This command module has a predefined set of command number definitions for use/reference.
:param dest_callsign: The callsign of the target Faraday unit
:param dest_device_id: The device ID number of the target Faraday unit
:param command: The command "number" that identifies the command packet to be parsed or direct action to be taken
:param payload: The payload for the specified command packet type. This is usually just commands full "packet" structure
:return: A complete command datagram packet as a string of raw bytes
"""
#Cheack if callsign is too long
if len(dest_callsign) < DEST_CALLSIGN_MAX_LEN:
#Define packet structures
pkt_cmd_datagram_struct = struct.Struct(
'2B25s'
) #Command packect to be run on remote unit as local command
pkt_cmd_datagram_error_detection_struct = struct.Struct(
'>1H'
) #Command packect to be run on remote unit as local command Error Detection
pkt_rf_cmd_struct = struct.Struct(
'9s2B29s'
) #RF Command packet that encapsulates local command to be run on remote unit
pkt_rf_error_detection_struct = struct.Struct(
'>1H') #16bit Error Detection (Checksum)
#Create local command for remote unit
pkt_cmd_datagram = pkt_cmd_datagram_struct.pack(
command, len(payload), payload)
pkt_cmd_datagram_error_detection = pkt_cmd_datagram_error_detection_struct.pack(
checksum.compute_checksum_16(pkt_cmd_datagram,
len(pkt_cmd_datagram)))
pkt_cmd_datagram_final = pkt_cmd_datagram + pkt_cmd_datagram_error_detection
print repr(pkt_cmd_datagram_final)
#Create RF Command for local device without Error Detection appended. NOTE Callsign must be in uppercase!
pkt_rf_cmd = pkt_rf_cmd_struct.pack(
str(dest_callsign).upper(), len(dest_callsign), dest_device_id,
pkt_cmd_datagram_final)
#Create final local command packet with Error Detection appeneded
pkt_rf_error_detection = pkt_rf_error_detection_struct.pack(
checksum.compute_checksum_16(pkt_rf_cmd, len(pkt_rf_cmd)))
packet = pkt_rf_cmd + pkt_rf_error_detection
return packet
else:
print "Error: Callsign too long!"
def create_command_datagram(command, payload):
"""
This function creates a command packet datagram that encapsulates the actual command packets to the parsed. This allows identification of packet "types" and modularity within the command system.
:param command: The command "number" that identifies the command packet to be parsed or direct action to be taken
:param payload: The payload for the specified command packet type. This is usually just commands full "packet" structure
:return: A complete command datagram packet as a string of raw bytes
.. note:: This command module has a predefined set of command number definitions for use/reference.
"""
#Define packets
pkt_struct1 = struct.Struct('2B')
pkt_struct2 = struct.Struct('119s')
pkt_struct3 = struct.Struct('>1H')
#Determine payload length
payload_len = len(payload)
#Create sub packets
pkt_a = pkt_struct1.pack(command, payload_len)
pkt_b = pkt_struct2.pack(payload)
checksum_computed = checksum.compute_checksum_16(pkt_a + pkt_b,
len(pkt_a + pkt_b))
pkt_c = pkt_struct3.pack(checksum_computed)
#Concactenate sub packets into a single packet
packet_packed = pkt_a + pkt_b + pkt_c
#Only return packet if all variables are correctly sized
if len(payload) <= FIXED_PAYLOAD_LEN_MAX:
#print "Lengths", len(packet_packed)
packet_final = packet_packed
return packet_final
else:
return False
print "ERROR - Create Command: Payload Too Long!", len(payload)
