No
. 96-1886-01E
Rev
.
1.1
GTECH Aircon Radio (Model GWT154)
PAGE
34
OF
72
0x15
NAK
0
Packet Negative Acknowledge
0x16
SYN
1
Set Peripheral Address / return
Status
0x17
ETB
Reserved
0x18
CAN
0
Abort packet request
0x19
EM
Reserved
0x1A
SUB
Reserved
0x1B
ESC
1
Exception prefix
0x1C FS
Unused
0x1D GS
Unused
0x1E RS
Unused
0x1F US
Unused
Table 13 - GTECH Packet Type Codes
7.1.3
GTECH
Address
Packet
The GTECH485 protocol uses query/response method to address individual Peripherals in a multi-drop
wired network. The Terminal issues a specific address command to select the active Peripheral, all
other Peripherals are to un-assert themselves from the bus. A reserved SYN (0x16) protocol character
is used to identify an address command packet.
Peripheral addresses are limited to a range between 0x21 and 0xFF. By default, if a peripheral
receives an address packet with an address other than its own, it is to un-assert itself from the bus.
The 802.15.4 radio module will need to parse the Host CPU interface serial stream for the GTECH485
protocol SYN character to properly route packets received from the Host CPU.
Bytes: 1
1
Fields: 0x16
SYN
0x21 <= a <= 0xff
Peripheral Address (a)
Structure 2: GTECH Address Packet
A peripheral addressed by an Address Packet is to reply with a response. The first byte is the repeated
address value. The second byte is a bit-mapped status byte. The radio module is required to send a
Response Packet when it is the addressed peripheral. At this time the Status will always be 0x00.
Note: Because the GTECH485 bus is a 4-wire bus, the radio does not receive another peripheral’s
Response Packet.
Bytes: 1
1
Fields:
0x21 <= a <= 0xff
Peripheral Address (a)
Address Status
Structure 3: GTECH Address Response Packet
