Schweitzer Engineering Laboratories SEL-2100, Инструкция по эксплуатации

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Date Code 20010529 Unsolicited SER Protocol I-1
SEL-2100 Instruction Manual
APPENDIX I: UNSOLICITED SER PROTOCOL
I
NTRODUCTION
This appendix describes special binary Sequential Events Recorder (SER) messages that are not
included in
Section 4: Serial Port Communications and Commands of the instruction manual.
Devices with embedded processing capability can use these messages to enable and accept
unsolicited binary SER messages from the SEL-2100.
SEL relays and communications processors have two separate data streams that share the same
serial port. The normal serial interface consists of ASCII character commands and reports that
are intelligible to people using a terminal or terminal emulation package. The binary data streams
can interrupt the ASCII data stream to obtain information, and then allow the ASCII data stream
to continue. This mechanism allows a single communications channel to be used for ASCII
communications (e.g., transmission of a long event report) interleaved with short bursts of binary
data to support fast acquisition of metering or SER data. To exploit this feature, the device
connected to the other end of the link requires software that uses the separate data streams. The
binary commands and ASCII commands can also be accessed by a device that does not interleave
the data streams.
M
AKE
S
EQUENTIAL
E
VENTS
R
ECORDER
(SER) S
ETTINGS
W
ITH
C
ARE
The SEL-2100 triggers a row in the Sequential Events Recorder (SER) event report for any
change of state in any one of the elements listed in the SER1 through SER6 trigger settings.
Nonvolatile memory is used to store the latest 32,768 rows of the SER event report so they can
be retained during power loss. The nonvolatile memory is rated for a finite number of “writes.”
An average of 333 state changes per minute can be made for a 25-year service life.
R
ECOMMENDED
M
ESSAGE
U
SAGE
Use the following sequence of commands to enable unsolicited binary SER messaging in the
SEL-2100:
1. On initial connection, send the SNS command to retrieve and store the ASCII names for the
digital I/O points assigned to trigger SER records. The order of the ASCII names matches the
point indices in the unsolicited binary SER messages. Send the “Enable Unsolicited Data
Transfer” message to enable the SEL-2100 to transmit unsolicited binary SER messages.
2. When SER records are triggered in the SEL-2100, it responds with an unsolicited binary SER
message. If this message has a valid checksum, it must be acknowledged by sending an
acknowledge message with the same response number as contained in the original message.
The SEL-2100 will wait approximately 100 ms to 500 ms to receive an acknowledge
message, at which time the SEL-2100 will resend the same unsolicited SER message with the
same response number.
3. Upon receiving an acknowledge message with a matching response number, the SEL-2100
increments the response number, and continues to send and seek acknowledgment for
unsolicited SER messages, if additional SER records are available. When the response
number reaches three it wraps around to zero on the next increment.