Rockwell Automation Publication 2080-UM002M-EN-E - April 2022 101
Chapter 6 Micro870 Controller Distributed Network Protocol
WRITE (FC Byte = 0x02)
02 – Write
The WRITE function code is used to write the contents of DNP3 objects from
the DNP3 master to the controller. This function code is used for clearing bit
IIN1.7 [DEVICE_RESTART], setting time in the controller and downloading
user programs to the controller.
SELECT (FC Byte = 0x03)
03 – Select
The SELECT function code is used in conjunction with the OPERATE function
code as part of select-before-operate method for issuing control requests. This
procedure is used for controlling binary output (CROB) or analog output
(AOB) objects.
OPERATE (FC Byte = 0x04)
04 – Operate
See SELECT (FC Byte = 0x03)
on page 101.
DIRECT_OPERATE (FC Byte = 0x05)
05 – Direct Operate
This direct operate function is similar to the FC_OPERATE function code
except that no preceding select command is required.
DIRECT_OPERATE_NR (FC Byte = 0x06)
06 – Direct Operate No Resp
See DIRECT_OPERATE (FC Byte = 0x05)
. No response message is returned
when this request is issued from a DNP3 master.
IMMED_FREEZE (FC Byte = 0x07)
07 – Immediate Freeze
Upon receiving a request with this function, the controller copies the current
value of a counter point to a separate memory location associated with the
same point. The copied value remains constant until the next freeze operation
to the same point.
IMMED_FREEZE_NR (FC Byte = 0x08)
08 – Immediate Freeze No Resp
See IMMED_FREEZE (FC Byte = 0x07)
. No response message is returned when
this request is issued from a DNP3 master.
FREEZE_CLEAR (FC Byte = 0x09)
09 – Freeze and Clear
Upon receiving a request with this function, the controller copies the current
value to the frozen value, then clears the current value to 0 immediately.
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