System Description

System Description and Installation Manual for MXS ICD10004-01
© Sagetech Corporation 2018 Confidential Proprietary Export-Controlled Page 24 of 160
The IP address and port number are configured in the installation message (Section 01.013.26.3.2).
3. Serial and Ethernet Message Format
The MXS serial and Ethernet interface uses the following message data structure for communication:
Table 0-2 Packet Structure
MessageField FieldDescription Number
bytes
Start Byte Precedes all messages with a fixed value of 0xAA. 1
Message Type Defines the message type. 1
Message ID Contains an arbitrary number between 0 and 255 (inclusive) that uniquely identifies the
message. (Typically, a sequence number.) Acknowledgement messages include the
Message ID of the command message being acknowledged. Sagetech recommends
incrementing this field by one with each message sent.
1
Payload Length Indicates the number of bytes in the Payload Data field. 1
Payload Data A variable length field with a different length depending upon the specific message. The
number of bytes in the Payload Data must match the Payload Length field. The Payload
Data contains the information that is used to control and command the MXS. The most
significant byte (MSB) of any data field is transmitted first.
0 to 255
Checksum Contains the regular 8-bit arithmetic summation of the message starting with the Start
Byte and ending with the last byte of the Payload Data. The summation is performed
assuming all bytes are unsigned, and the result is truncated to the least significant 8 bits.
1
12. Operating Modes
The MXS can operate in the following modes:
OFF – In this mode there is no communication of any kind. The MXS device consumes near zero power. This mode is
set using the MXS Power Control pin on the main connector. (See Section 105.1)
STBY (Standby) – In this mode, transmitting is unavailable and receiving is available. In Standby, MXS is in low power
mode with minimal components active, including the microprocessor and communication ports. STBY is set using the
Operating Message. (See Section 13.46.3.4)
ON –In this mode the transponder is operational but inhibited from transmitting any pressure altitude information. ON is
set using the Operating Message. (See Section 13.46.3.4)
ALT – In this mode the MXS is fully operational, including transmitting altitude, if available. ALT is set using the
Operating Message. (See Section 13.46.3.4)