ERNITEC LON Box I151SX, Руководство по установке

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Alarm Command
One ASCII character.
Alarm ON is "A" (41 Hex). Alarm OFF is "C" (43 Hex).
Alarm Number
Alarm number in ASCII format ("Number
1
" ~ "Number
n
").
Checksum
The XOR result of all previous bytes, including Header
Xon/Xoff Flowcontrol
The SAP protocol uses Xon/Xoff flowcontrol. The Xon character is DC1 (11 hex), and Xoff is
DC3 (13 hex).
The Xon/Xoff principle is as follows:
When the receiver buffer is 80% full, the receiver transmits an Xoff character to stop the
transmitter. When the buffer is only 20% full the receiver transmits an Xon to start the
transmitter again.
To be able to send both DC1 and DC3 as data, the protocol uses "the character stuffing
principle". Character stuffing means that the transmitter is transmitting an extra DC1
character if it wants to transmit DC1 as data. Then the receiver knows that two DC1
characters means "DC1-data" and one DC1 means "Xon".
Example
In order to set alarm number 45 ON, the following string must be transmitted:
53 05 41 34 35 16
53: "S" - Header
05: Number of bytes
41: "A" - Alarm ON
34,35: "45" Alarm number
16: XOR checksum (53 xor 05 xor 41 xor 34 xor 35)
IEC Alarm Protocol
Information about the IEC protocol can be found in the Ernitec Protocol Manual, available on
request.
S Y S E M
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