G-6 Appendix G Date Code 20010518
SEL-2020 Instruction Manual
Force Single Coil (Function Code 05h)
The SEL-2020 uses this function code for a variety of data control purposes. Specifically, you
can use it to clear archive records, hold copies of data records, release copies of data records,
and operate breaker and remote bit elements.
The master request must have the following format:
1 byte Slave Address
1 byte Function Code (05h)
2 bytes Coil Reference
2 bytes Operation Code
2 bytes CRC-16 for Message
A successful SEL-2020 response will be an echo of the request message.
There are six special purpose coil references:
0000h Clear archive record using function code 04h addressing
0003h Copy a region using function code 04h addressing
0004h Release a region copy using function code 04h addressing
0010h Clear archive record using function code 03h addressing
0013h Copy a region using function code 03h addressing
0014h Release a region copy using function code 03h addressing
Coil references 0000h and 0010h are for clearing archive records. The operation code must be
the starting address of the record to clear. Once you clear an archive record, subsequent reads
from that region will return data from the next record stored in that region.
CAUTION
!
Frequent archive record clearing may exceed EEPROM
capabilities. See the discussion in the Archive Data Region
subsection of Section 9: Database.
Coil references 0003h and 0013h cause a copy of the specified region to be made. Subsequent
reads from this region will read from your copy. This allows you to read data regions that are
larger than 125 registers without the data changing between accesses. Specify the region to copy
by giving its starting address as the operation address. Use coil references 0004h and 0014h to
release the region copy once you are done with it. If there is insufficient memory to make the
requested copy, the SEL-2020 will respond with a BUSY exception code.
For coil references 0000h, 0003h, and 0004h, the operation code must correspond to a modified
map address (map function code 04h uses). For operation code 0010h, 0013h, and 0014h, this
starting address must correspond to a true database address.
Coil references 10AOh through 10BFh correspond to the port breaker and remote bit elements:
10A0h - 10A7h correspond to BR8 - BR1
10A8h - 10Afh correspond to BR16 - BR9
10B0h - 10B7h correspond to RB8 - RB1
10B8h - 10BFh correspond to RB16 - RB9
Send a coil ON (operation code FF00h) to set the bit and OFF (operation code 0000h) to clear
the bit.
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