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Electronic Theatre Controls Inc

USAP Packet Information

All information necessary to define each command is supported. For example, a preset is defined by what section of a room it is in, what priority it has, and what fade time it has. Only necessary information needs to be provided over the communications link. If no fade time and priority are sent, the preset will run using the default priority and fade time.  

Commands return an acknowledgment that the command was activated. Commands that are not recognized return an error message. All commands are case-sensitive.

USAP Frame Format

USAP frame segments are always represented by hexidecimal values. The graphic below indicates which frame segments are predefined and which frame segments require user defined information.

  • Length is the number of bytes until CRC, or size of data plus 3. Again, this value, as well as the others must be represented in hexidecimal. See Decimal to Hex Conversion Chart.
  • **Data is the command to be sent in ASCII (see Data Structure). The data portion of the packet should be less than 200 bytes long.
Start code Length Command ID Protocol Data CRC
0xEE (*varies) 0x00 0x00 0x40 (*varies) 0x0000

All frames should be formatted as indicated in the graphic above. Start code, Command, ID, Protocol, and CRC segments always have the values indicated.

Sample USAP Frame Format

In the following USAP packet example, the preset named "Dinner" in the room "Ballroom" will be activated.

Sample USAP Frame Format.png


Note: RS-232 devices or systems interfacing with the Unison system may require additional characters before a hex value. Know your system requirements prior to programming.  

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