Moog Crossbow GNAV540 - Manual (Page 67)

GNAV540 User Manual
7430‐0808‐01 Rev. B Page 67
Chapter 9. Communicating with the GNAV540
Communication commands are used to verify a unit is present and alive.
Unit
Ping Command
Table 15 Ping Command
Ping (‘PK’ = 0x504B)
Preamble Packet Type Length Termination
0x5555 0x504B ‐ ‐
The ping command has no payload. Sending the ping command will cause the unit to send a ping response. To
th and CRC fields are not required. facilitate human input from a terminal, the leng
Example: 0x5555504B009ef4 or 0x5555504B
Ping Response
Ping (‘PK’ = 0x504B)
Preamble Packet Type Length Termination
0x5555 0x504B 0x00 <CRC (U2)>
The unit will send this packet in response to a ping command.
Echo Command
Table 16 Echo Command
Echo (‘CH’ = 0x4348)
Preamble Packet Type Length Payload Termination
0x5555 0x4348 N <echo payload> <CRC (U2)>
The echo command allows testing and verification of the communication link. The unit will respond with an echo
response containing the echo data. The echo data is N bytes long.
Echo Response
Table 17 Echo Response
Echo Payload Contents
Byte
ffset O
Name Format Scaling Units Description
0 echoData0 U1 — — first byte of echo data
1 echoData1 U1 — — Second byte of echo data
… … U1 — — Echo data
N‐2 echoData... U1 — — Second to last byte of echo data
N‐1 echoData… U1 — — Last byte of echo data