Comtech EF Data CRS-500, Инструкция по установке и эксплуатации

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CRS-500 1:N Redundancy System
Revision 4
Serial Interface Operation 10–3 MN-CRS-500
10.2.3 Basic Serial Protocol
Serial data can be transmitted and received by a Universal Asynchronous Receiver/Transmitter (UART). Serial data is transmitted as
asynchronous serial characters:
•
Asynchronous character format is 8-N-1 (8 data bits, no parity, 1 stop bit)
•
Baud rate can vary from 300 through 19,200 baud.
Serial data is transmitted in framed packets. All bytes within a packet are printable ASCII characters less than ASCII code 127 (DELETE).
The Carriage Return and Line Feed characters are considered printable.
The Controller device manages the monitor and control processes. It is the only device that can start data transmission at will. Messages
sent from the Controller to the Target require responses, except in these cases:
•
Acknowledging receipt of a “command” – an instruction message issued by the Controller – to change the configuration of the
Target.
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Returning data that was requested by the Controller – response to a “query” message – that requests information from the Target.
Target devices can transmit data only when the Controller tells them to.
10.2.4 Rules for Remote Serial Communications with the CRS-500
1. Always wait for a response (up to 15 seconds) from the CRS-500 before sending the next query or command.
2. If a "time-out" response ('~') is sent from the CRS-500, the user must resend the previous command. The ‘~’ response indicates
that a pass-through command to a modem/transceiver attached to the CRS-500 has "timed-out" and there was no response from
the other device. During this wait, do not communicate with the CRS-500. After the '~' response is sent by the CRS-500, it is now
ready to receive a message again. The CRS-500 knows to wait different times for the different messages it is sending to modems:
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Status queries (no commands) are fast, (typically less than 333 ms).
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Configuration changes (commands) take longer and vary by modem type.
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Individual commands responses are faster than those to global commands (MGC). More parameters require more time.
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A pass-through command is passed with little inspection by the switch, but keep in mind that the modem being addressed
may be at the distant end of an EDMAC link! Types of pass-through commands:
o
To a local modem;
o
To a modem at the distant end (EDMAC);
o
To a local BUC or transceiver connected to a local modem;
o
To a distant end BUC or transceiver through the distant end modem.