Date Code 20010518 Appendix G G-11
SEL-2020 Instruction Manual
5. Next, issue the command SET A 2 to set an auto-message to collect relay meter data.
Respond to prompts about saving unsolicited messages (AUTOBUF) and the STARTUP
string. Press <ENTER> to confirm the defaults for both prompts. Enter 1 when prompted
for the message count. At the ISSUE1 prompt, enter P00:00:01 to set the message to trigger
once every second. At the MESG1 prompt, enter 20METER to send the request for meter
data to the SEL relay. Press <ENTER> to accept the default for remaining settings and enter
Y to save changes. As soon as the SEL-2020 accepts the setting change, the TXD and RXD
Port 2 LEDs on the SEL-2020 will begin to flash as the SEL-2020 requests and receives
meter data every second.
6. Confirm that the meter data are collected in binary format by issuing a MAP 2 command.
The D1 region should show a “B” preceding the METER data type, indicating binary
collection.
7. View the data stored in the Port 2 METER data region by issuing the command VIEW
2:METER or VIEW 2:D1. The SEL-2020 responds with a data “dump” showing the data
stored in the region at the time of the request with the respective data item labels. In this
example, the data are updated once each second.
8. Cause the Modbus master to send a “read PORT 2 METER region” message. In the
message, the slave address field is the Port 2 address set in Step 3. The Register Address
field is METER (100). The Register Count is the meter data length for SEL-321-1. (See
Table G.1 for the register map.) The returned METER data are the same as the data
displayed by the VIEW command if the data have not been updated since issuing the VIEW
command. The following shows a typical exchange:
Received message:
06
04
00
64
00
60
xx
xx
to address 6
function code 4
starting register address 100
read 96 registers
CRC-16 code
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