Date Code 20090730 Instruction Manual SEL-734 Meter
Appendix C
SEL Communications Processors
SEL Communications Protocols
The SEL-734 Meter supports the protocols and command sets shown in
Table C.1.
SEL ASCII Commands
We originally designed SEL ASCII commands for communication between
the meter and a human operator via a keyboard and monitor or a printing
terminal. A computer with a serial port can also use the SEL ASCII protocol
to communicate with the meter, collect data, and issue commands.
SEL Compressed
ASCII Commands
The meter supports a subset of SEL ASCII commands identified as
Compressed ASCII commands. Each of these commands results in a
comma-delimited message that includes a checksum field. Most spreadsheet
and database programs can directly import comma-delimited files. Devices
with embedded processors connected to the meter can execute software to
parse and interpret comma-delimited messages without expending the
customization and maintenance labor needed to interpret nondelimited
messages. The meter calculates a checksum for each line by numerically
summing all of the bytes that precede the checksum field in the message. The
program that uses the data can detect transmission errors in the message by
summing the characters of the received message and comparing this sum to
the received checksum.
Most commands are available only in SEL ASCII or Compressed ASCII
format. Selected commands have versions in both standard SEL ASCII and
Compressed ASCII formats. Compressed ASCII reports generally have fewer
characters than conventional SEL ASCII reports, because the compressed
reports reduce blanks, tabs, and other “white space” between data fields to a
single comma.
Table C.1 Supported Serial Command Sets
Command Set Description
SEL ASCII Use this protocol to send ASCII commands and receive
ASCII responses that are human readable with an appropriate
terminal emulation program.
SEL Compressed ASCII Use this protocol to send ASCII commands and receive
Compressed ASCII responses that are comma delimited for
use with spreadsheet and database programs or for use by
intelligent electronic devices.
SEL Fast Meter Use this protocol to send binary commands and receive
binary meter and target responses.
SEL Fast Operate Use this protocol to receive binary control commands.
SEL Fast SER Use this protocol to receive binary Sequence Events Recorder
unsolicited responses.
Courtesy of NationalSwitchgear.com
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