DNP3 Master

In Master mode inSCADA connects to field devices (RTUs, IEDs, relays and the like) to read data and send control commands.

Data model

Step 1: creating the connection

Parameter	Example	Description
Protocol	DNP3	The protocol
IP Address	192.168.1.50	The target outstation’s IP address
Port	20000	The target port (default: 20000)
Adapter	(empty)	The network adapter (for a host with several NICs)
Pool Size	1	The connection pool size
Min Retry Delay	1000 ms	The shortest wait before reconnecting
Max Retry Delay	60000 ms	The longest wait before reconnecting

Step 2: creating the device

Parameter	Example	Description
Local Address	1	The master’s DNP3 address
Remote Address	10	The outstation’s DNP3 address
Response Timeout	5000 ms	How long a response is waited for
Integrity Scan Time	60000 ms	The integrity scan interval (all static data)
Event Scan Time	5000 ms	The event scan interval (class 1/2/3)
Scan Type	PERIODIC	PERIODIC or FIXED_DELAY
Unsolicited Events	true	Accept unsolicited responses
Disable Unsolicited on Startup	false	Turn unsolicited off at startup
Startup Integrity	true	Run an integrity scan at startup
Integrity on Event Overflow IIN	true	Run an integrity scan when the event buffer overflows

Tip

An integrity scan polls all static data and takes a full copy of the outstation’s database. An event scan brings back only what has changed since the last one.

Step 3: creating frames

Define one frame per data group:

Parameter	Example	Description
Type	Analog Input	The data type
Start Address	0	The first point index
Quantity	10	How many points
Event Buffer Size	100	The event buffer size
Point Class	Class 1	The event class
Static Variation	Group30Var5	32-bit float (with flag)
Event Variation	Group32Var7	32-bit float (timestamped)
Deadband	0.5	The analogue event threshold

Typical frames

Frame name	Type	Start	Quantity	Used for
Analog Inputs	Analog Input	0	20	Temperature, pressure and current measurements
Binary Inputs	Binary Input	0	32	Digital state information
Counters	Counter	0	8	Energy meters
Binary Outputs	Binary Output	0	16	Control outputs

Step 4: creating variables

Parameter	Example	Description
Start Address	0	The point index
Point Class	Class 1	The event class (may be inherited from the frame)
Static Variation	Group30Var5	The static data format
Event Variation	Group32Var7	The event data format
Deadband	0.5	The analogue event threshold

Step 5: starting the connection

Start the connection from the Runtime Control Panel. Its status will show “Connected”.

Control commands

The master can send an outstation:

• Select-Before-Operate (SBO): select first, then operate — the safe form of control
• Direct Operate: operate immediately
• Freeze Accumulator: freeze a counter
• Time synchronisation: set the outstation’s clock