APPENDIX
This Appendix details the elements for communication between the Video Multiplexer and the personal computer. For BAUD RATE, DATA BIT, STOP BIT and PARITY settings, see page 42 COM PORT SETUP menu.
●Communication Protocol
1. Transmission Command
The PC sends messages to operate the Multiplexer in the format shown below. Also refer to the command table shown later.
Code | [STX] | [Address] [;] [Transmission Command] | [ETX] |
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ASCII | (02H) | ( ) – – – – – – – – – – – – – – – – – ( ) | (03H) |
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A transmission message consists of [STX], [Address], [;], [Transmission Command], and [ETX]. [Address] is expressed as “ADuu,”where ‘uu’ is in the range of “00” through “16” in decimal form to identify the unit number of the Video Multiplexer. When using the
2. Response Command
The Multiplexer returns messages in reply to the PC’s messages with the following formats.
(1) Reception completed
When the reception was completed successfully, the Multiplexer sends back “ACK code, 06H”, followed by parameters. The response command is shown in the Command Table.
Code | [STX] | [Address] [;] [Response Command] | [ETX] |
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ASCII | (02H) | ( ) – – – – – – – – – – – – – – – ( ) | (03H) |
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(2) Reception error
The Multiplexer sends back “NAK code, 15H”, followed by the parameters shown below. The Multiplexer then resets the reception buffer and enters waiting mode for the next message. Parameter “e” identifies the error status.
Code | [NAK] [e] |
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ASCII | (15H) |
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“e” value | 1: Parity error | |
| 2: Data Over error | |
| 3: Framing error | |
| 4: Overrun error | |
| 5: Time Out error | |
(3) Parameter error
The Multiplexer returns “ACK code, 06H”, the transmission command that was not processed properly for some reason, followed by an error code as shown below.
Code | [STX] | [Transmission Command] | [:] | [Error Code] | [ETX] |
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ASCII | (02H) ( | ) – – – – – – ( ) (3AH) | ( | ) – – – ( ) | (03H) |
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Error code | ER001: Command invalid |
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| ER002: Parameter invalid |
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ER301: Command legal but out of range
ER302: Parameter legal but out of range
Note: The Video Multiplexer returns [ACK] or [NAK] to the PC within 20 ms after the reception of [ETX] in a transmission mes- sage.
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