
Chapter 13
DNP 3.0 and MODBUS Data
Structures
13.1
Introduction
Arbiter Systems provides additional capability and flexibility for data acquisition within the Model
1133A by supporting both DNP 3.0 and Modbus protocols.
Prior to using a DNP 3.0 or Modbus application to access 1133A data, configure the 1133A for
these protocols using PSCSV software. To set up the 1133A for use with Modbus or DNP 3.0, see
“Configuring Modbus Protocol” and “Configuring DNP 3.0 Protocol” in Section 7.
The majority of information in this section consists of the tables of index values used to access
1133A data from other software applications specifically designed for use with DNP 3.0 or Modbus.
While these index codes have been tested successfully, Arbiter Systems has no control over the
performance and suitability of using these applications with the Model 1133A, and makes no claim
or warranty in this regard.
13.2
Definitions and Conventions
13.2.1
DNP 3.0
DNP 3.0 is an industry standard SCADA communications protocol originating in the electric
industry in the USA. DNP 3.0 describes standards for SCADA protocol facilities such as data
requests, polling, controls, and report by exception (RBE), where master-slave and peer-to-peer
communication architectures are supported. A master device issues commands and the slave device
responds to the commands.
Using DNP 3.0, the Model 1133A is considered a slave device that only responds to commands
from the master with data or status. The 1133A cannot be configured using DNP 3.0. Configure
the 1133A only through PSCSV software.
13.2.2
Modbus
Modbus Protocol is a messaging structure, widely used to establish master-slave communication
between intelligent devices. A Modbus message sent from a master to a slave contains the address of