Sony EVI D100 Technical Manual - Page 19

VISCA Communication Specifications VISCA packet structure The basic unit of VISCA communication is called a packet (Fig. 2). The first byte of the packet is called the header and comprises the sender's and receiver's addresses. For example, the header of the packet sent to the EVI-D100/P assigned address 1 from the controller (address 0) is hexadecimal 81H. The packet Command List sent to the EVI-D100/P assigned address 2 is 82H. In the command list, as the header is 8X, input the address of the EVI-D100/P at X. The header of the reply packet from the EVI-D100/P assigned address 1 is 90H. The packet from the EVI-D100/P assigned address 2 is A0H. Some of the commands for setting EVI-D100/P units can be sent to all devices at one time (broadcast). In the case of broadcast, the header should be hexadecimal 88H. When the terminator is FFH, it signifies the end of the packet. Header Packet (3 to 16 bytes) Message (1 to 14 bytes) Byte 1 Byte 2 Byte 3 Terminator FF Sender's 1 address 0 Receiver's address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (MSB) (LSB) 11 11 1111 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (MSB) (LSB) Fig.2 Packet structure Command and inquiry G Command Sends operational commands to the EVI-D100/P. G Inquiry Used for inquiring about the current state of the EVI-D100/P. Command Packet Note Inquiry 8X QQ RR ... FF QQ1) = Command/Inquiry, RR2) = category code 1) QQ = 01 (Command), 09 (Inquiry) 2) RR = 00 (Interface), 04 (camera 1), 06 (Pan/Tilter) X = 1 to 7: EVI-D100/P address 19