Communication Protocol; Header; Payload - Sim2 D35 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.
Each packet received by the projector is acknowledged with a return code:
- : Acknowledged with no error
06
- : Acknowledged, but an error has occurred.
15

Header

All Packets use the same Packet Header format.
The Packet Header size is fixed at seven bytes.
0
BE
0xEFBE is a fixed value that is used to insure packet alignment if there are partial packets received or byte
lost. The ls-byte of the word 0xBE is sent first, then the ms-byte 0xEF.
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:
0
Event
Operation Packet Format:
0 1
Op Type Operation ID
13 14
00 00
1 2
Packet Type
EF
1 2
00
2 3 4
00 00
15 16 17
00 00 00
3
Packet Payload Size
3 4
00 00
5 6 7
Target
18 19 20
00 00 00
4
RS-232C CONTROL SPECIFICATIONS
4 5
Packet Checksum (CRC)
5
00
8 9 10
Operation Value
21 22 23
00 00 00
SIM2 D35
6
11 12
00 00
24
00