Commands and Responses Overview
The external control protocol is standard ASCII based. ESCX is the four letter preamble that is used for all commands. This preamble must be uppercase. The commands provided in this protocol allow an external control system to navigate the Escient products, get library informa- tion to build custom user interfaces, perform transport controls, and receive unsolicited feedback on system status.
All external control commands are made up of the preamble (ESCX), command group (01,02,10,20,50,70), sub command (specific task), specific data (# of data items, and a size of data packet then the actual data packet repeated for the # of data items), and a carriage return end marker.
External Control Command Structure
DESCRIPTION | PREAMBLE | COMMAND GROUP | SUB COM- MAND | # DATA ITEMS | DATA ITEM #1 SIZE | DATA #1 | DATA ITEM #2 SIZE | DATA #2 | END MARKER |
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Bytes | 4 | 2 | 2 | 3 | 4 | 5 | 4 | 3 | 1 |
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Example | ESCX | 01 | 08 | 002 | 0005 | Hello | 0003 | Bye | Carriage Return |
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The external control commands are broken down into the following Command Groups:
01 – Command Responses
02 – Unsolicited Events
10 – Remote Button / Keyboard Commands
20 – Database Commands
50 – Status Commands
70 – Control Commands
APPENDIX D- EXTERNAL CONTROL PROTOCOL
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