9-2 Database Date Code 20010518
SEL-2020 Instruction Manual
The region sizes shown in Table 9.1 indicate the maximum amount of data that can be stored in
each region. The actual data stored in each region of each port depends on the settings you apply
using the SET A command.
If you set AUTOBUF=Y on a port, unsolicited messages are stored in the BUF region until the
region is cleared, or until the region is completely filled. When the BUF region is filled, the
newest data will overwrite the oldest data as they are received.
The data regions D1 to D8 store data solicited by messages you create with the ISSUEx and
MESGx settings. The data you solicit using “20” messages are parsed automatically in the asso-
ciated data region. All of the “20” message responses will fit in any of the data regions, except
the response to the 20EVENT, 20EVENTS, and 20EVENTL messages. These messages elicit an
event report from an SEL relay. Only the D3 and A3 data regions are large enough to hold an
entire 20EVENT or 20EVENTS event report response and only the A3 region is large enough to
hold a 20EVENTL event report response.
You control the size of the data solicited with non-“20” messages based on the parsing method
you choose and the size of the message response you define with the NUMx setting. If you
specify a size larger than the region size, the SEL-2020 will respond immediately with an “Out of
Range” message.
You can only reference those portions of regions that have data assigned. If you reference an
address that is not assigned, the SEL-2020 will respond with a message that the data address does
not exist.
You allocate all, or a portion, of the User data region with the SET A command, or the SET M
command automatically allocates the User data region. You must use the STORE command,
user-defined write command, or Modbus write function code to put the data into this area. You
may also use SET M to establish automatic storage of data into the User region.
Archive regions are unique from other regions. Where all other regions contain only a single
record, the archive regions contain a queue of records. From a data access point of view, the
archive regions appear to only contain the oldest record. But, as soon as it is cleared, the next
oldest record will appear. The number of archive records that can be stored is only limited by the
amount of nonvolatile Flash memory.
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