2-10 General Description Date Code 20010518
SEL-2020 Instruction Manual
D1 to D8 Regions
For all ports, except the front port, the database includes data regions D1 to D8, allocated for
data solicited by the SEL-2020. The first four registers of each region hold the date and time the
data were collected. The remainder of each region is for the collected data. How the information
is parsed, or separated into useful groups, will depend on the type of data and how it is collected.
Each data region is associated with a message created using the SET A command. For example,
the response from Message 1 will be captured in data region D1 and Message 2 response in data
region D2. Responses from “20” messages, which include the following, are parsed automati-
cally:
20METER, 20TARGET, 20DEMAND, 20HISTORY, 20STATUS, 20BREAKER,
20EVENT, 20EVENTS, and 20EVENTL.
Data received in response to non-“20” messages are parsed according to the parsing option you
selected in the SET A automatic message settings. Non-“20” message parsing options include
the following:
Ignore, ASCII Integer, ASCII Floating-Point, Character String, Integer String, and Integer
String with XON/XOFF encoding.
Each response is time-tagged by the SEL-2020 at the time it begins receiving the message. Data
collected in regions D1 to D8 are held until the next data are received; the new data overwrites
the old data. The SEL-2020 will assign a data label to each data region, depending on the
message content and parsing method you choose. For example, if you set Message 1 on Port 1 to
collect meter data from an SEL relay using the 20METER command, the region 1:D1 will be
assigned a data label of METER. This label can be very helpful when you address the region to
MAP or VIEW the data, or to retrieve specific data items from the data region.
A1 to A3 Regions
The archive data regions, A1 to A3, are only available if the SEL-2020 is equipped with optional
nonvolatile Flash memory. These regions are designed for long-term storage of information,
such as SEL relay long event reports and meter demand data. Each archive data region works on
a First-In-First-Out (FIFO) basis, much like long event report storage in SEL relays. The number
of records that can be stored in each region depends on the size of each record. Individual
records can be viewed, retrieved, and cleared.
User Region
The User region is available on each port for any purpose you desire. You can write data to this
area from a master device using the STORE command or the special user-defined data WRITE
command. You can also copy data here from other regions for centralization and custom
organization using the SET M command. Any port can then use data in this region to construct
messages.
Database Tools
The SEL-2020 Command Set contains several commands to help you check that requested data
are placed in the proper database location and to ensure that the data requests and responses are
not overrunning each other, or interfering with each other.
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