Introduction

This section gives specific details on the configuration and operation of the DNPScanner.

The following symbol indicates a reference to the specified section in section 4 of the RTAP/Plus Integration Manual§.

The DNP 3.0 protocol is as described in "Distributed Network Protocol DNP 3.0 Basic 4 Document Set, Part Number: 994-0007 November, 1993, Rev. 01".

The DNP 3.0 scan task supports the following set of objects:

Binary Input -- Object 01, all variations
Binary Input Change -- Object 02, all variations
Binary Output -- Object 10, all variations
Control Relay Output Block -- Object 12, variation 01
Pattern Control Block -- Object 12, variation 02
Pattern Mask -- Object 12, variation 03
Counters -- Object 20, all variations
Frozen Counters -- Object 21, all variations
Counter Change Event -- Object 22, all variations
Frozen Counter Event -- Object 23, all variations
Analog Input -- Object 30, all variations
Frozen Analog Input -- Object 31, all variations
Analog Change Event -- Object 32, all variations
Frozen Analog Change Event -- Object 33, all variations
Analog Output Status -- Object 40, all variations
Analog Output Block -- Object 41, all variations
File Identifier - Object 70, variation 01
Short Floating Point -- Object 100, variation 01

The following set of objects are supported but not directly in the scan input/scan output table:

Object	Description
Time and Date – Object 50, variation 01	This object is sent to the remote device when the internal indications returned from it indicates that it requires a time sync. The time sync is sent on the next read or write message.
Time and Date CTO – Object 51, variation 01/02	This object is received from the remote device when an object requiring a relative time measurement is requested for.
Time Delay – Object 52, variation 01/02	This object is received from the remote device when the time sync attribute is set appropriately. It is also received when using the function codes: Cold Restart (13) Warm Restart (14) Start Application (17) Save Configuration (19) Delay Measurement (23)
Device Profile – Object 82, variation 01	This object is received from the remote device. The information from this object is logged through RtapMonitor, and printed to the debug device if the debug level is greater than six.

The DNP scan task uses the RTAP PRBX (Polled Report By eXception) to request for class data. The PRBX type zero maps to class zero, PRBX type one maps to class one, PRBX type two maps to class two and PRBX type three maps to class three. All other PRBX types will be ignored. In order for the class data response to be properly processed, the unsolicited field in the scan input table must be set to one for those objects.

Unsolicited requests from the RTU is currently only supported on the UNIX version and with the TCP/IP or UDP/IP connections on the Windows version.

Polling for event objects may result in no response from the end device. In this case, the scan task will not mark object(s) not returned in the response as failed.

The DNP scan task supports the following scan system access:

rtControlScanSys -- with the following device dependent actions being supported:
- rtCNTRL_FORCE_POLL
- rtCNTRL_FORCE_POLL_TYPE
- rtCNTRL_PRIORITY_POLL
- rtCNTRL_PRIORITY_POLL_TYPE
- rtCNTRL_FORCE_PRBX
- rtCNTRL_FORCE_PRBX_TYPE
- rtCNTRL_COLD_RST_DEVICE
- rtCNTRL_WARM_RST_DEVICE
- rtCNTRL_SET_TIME
with rtE_ST_FUNC_UNSUPPORTED returned for the following control actions:
- rtCNTRL_SNAP
- rtCNTRL_SNAP_WITH_VERIFY
rtQueryScanSys
rtReadFromScanSys
rtWriteToScanSys

The DNP scan task does not support the rtDirectCmdSS function.

This version of the DNP scan task allows a TCP/IP or UDP connection through a socket (see socket, socket info, and socket index). To switch between different sockets, send an rtUSER_MESSAGE message type to the scan task after the socket index has been changed to the new host/service record. This will cause the scan task to close the current socket connection, and re-open a socket connection to the specified host/service.

The DNP scan task also allows the user to extend it's functionality by adding support for other objects and/or over-ride any existing objects functionality (see Extending the DNP Scan Task).

Currently available only for the UNIX version.

In order to allow the transfer of multiple values through the scan task buffer, two special CE functions have been developed as part of the release (see Device Independent Fields Treated Specially ).

This implementation of the DNP protocol restricts the maximum application fragment size to 2048 bytes. Outgoing application fragments can be adjusted below this value by setting max data size. A silent maximum for this value is 2048. A check for a maximum incoming (RTU response) application fragment size can be made by specifying max recv size.