PACSystems™ RX3i DNP3 Outstation User Manual
Section 5
GFK-3103B
June 2020
System Operation
52
5.1
Controller and DNP3 Outstation Communication
The CPE400/CPL410 and CPE115 during normal operation, handles asynchronous requests from its
various DNP3 masters at designated portions of the CPU scan. It performs all these tasks without
burdening the CPU beyond the windows designated for data exchange.
On power-up or reset the DNP3 application in controller will wait for the PME configuration. Once PME
receives its configuration parameters, the DNP3 application scans the data, based on the information
provided. The DNP3 application detects and registers data changes within the controller. It also
services asynchronous DNP3 master requests for polling and writing of data to PLC reference memory.
The DNP3 application polls the CPU during the CPU background scan window for data, per its
configuration. The application detects and records all corresponding data changes internally.
Whenever master sends a write request, the application must wait for the corresponding scan window
to allow it to write the information into the PLC Reference memory during the same window.
5.2
Strict Connection Control Parameters
The DNP3 Outstation application code is capable of enforcing strict acceptance of connections to the
Outstation by DNP3 master stations. There are two general parameters which govern this feature and
corresponding parameters for setting the incoming connection masks. This functionality is also
referred to as white listing.
The Outstation allows the establishment of a white list of allowed connections, both TCP/IP and LLA
Master Station addresses. The TCP/IP white listing can be enabled independently where as LLA white
listing by default enables TCP/IP white listing.
Parameters used to configure the DNP3 Outstation to operate in a restrictive connection mode are:
CPE400/CPL410:
•
Validate Source IP
•
Validate Source Address
CPE115 DNP3 Configuration Using SVC_REQ:
Table 16: Whitelisting Parameters
Parameter
Description
mDNP3_Setup [89]
Validate Source IP
mDNP3_Setup [122]
Validate Source Address
Whenever parameters Validate Source IP and Validate Source Address are Disabled, the DNP3
Outstation will accept connections from any master station without regard to it source IP or address.
For HSB System, Validate Source IP and Validate Source Address are enabled by default and are
required to maintain integrity of events generated between the ACTIVE and BACKUP units. In case of
failure in current ACTIVE unit, the BACKUP unit will take over and all the masters connected to the new
ACTIVE unit will get their respective events.