ProSoft Technology MVI71-DNP - Manual (Page 106)

MVI71-DNP ♦ PLC Platform Reference
DNP 3.0 Master/Slave Communication Module
Page 106 of 172 ProSoft Technology, Inc.
August 23, 2007
The PLC transfers data of this type to the module using COP command. The
module maintains two values for each counter point: a current running value and
a frozen value. The DNP master must send the freeze command to the module in
order to transfer the current running values to the frozen area. Additionally, the
DNP master can send a freeze/clear command to the module. This causes the
frozen counter area to be updated with the current running values, and then the
current running values are reset to zero. The values will only be zeroed in the
module's counter database and not in the PLC.
Data from IED units can also
be placed in the DNP counter data area. Commands in the command list must
specify the DNP database address (point number) where the data will be placed.
Both frozen counter and counter data values obtained from the IED units are
placed in the counter data. The frozen counter data is only updated on a request
from the remote DNP master. The counter data from the IED units can be read
by the remote DNP master unit connected to the DNP slave port.
The following shows a data flow diagram for the counter data:
All the current running counter data is transferred from the PLC to the module
using the BTW instruction and blocks 40 to 55. This provides for a maximum
number of 480 counter values.