Communication Protocol, Header, Payload | Sim2 Multimedia C3X Link

SIM2 C3X LINK

RS-232C CONTROL SPECIFICATIONS

3. Communication Protocol

The communication protocol is packet oriented. Packets consists of Header and Payload.

There are two types of packets: Event and Operation.

The packet header size is fixed (7 bytes), while the packet payload type and content varies based on the type of packet: Event payload size is 6 bytes, while Operation payload size is 25 bytes.

The entire packet size is variable, being the sum of the fixed-size packet header and variable-sized packet payload: Event packet size is 13 bytes and Operation packet size is 32 bytes.

Header

All Packets use the same Packet Header format.

The Packet Header size is fixed at seven bytes.

Packet Type

Packet Payload Size

Packet Checksum (CRC)

0xEFBE is a fixed value that is used to insure packet alignment if there are partial packets received or byte lost. The least-significant byte of the word (BE) is sent first, then the most-significant-byte (EF).

The Packet Type is a number (a byte in length) that defines the type of data in the packet.

The Packet Payload Size is a number (two bytes) that defines the size of the payload portion of the packet. For a given Packet Type, Packet Size is fixed.

The Packet Checksum (two bytes) is the CRC value for the entire packet (Header and Payload).

Payload

The packet payload format depends on the packet type.

The Event packet payload size is 6 bytes, while the Operation packet payload size is 25 bytes.

Event Packet Format:

Event

Operation Packet Format:

Op Type

1 2

Op ID

5 6

Op Target

9 10 11

Op Value	00

13	14	15	16	17	18	19	20	21	22	23	24