There are two ways to map Modbus registers to RTU point addresses. Both are set up using SCADAPack E Configurator.
- Customized address mapping is the recommended method for new configurations. It allows you to assign a specific 5-digit or 6-digit Modbus register, or address, to a DNP3 point or a range of DNP3 points and to easily view the one-to-one mapping. Once you use this method to map a single Modbus register, automatic addressing mapping is disabled. Firmware/Configurator 8.11.1 is needed to use this feature
- Automatic address mapping is the default method for mapping Modbus registers to DNP3 points. It requires no user configuration, except in the case of 32-bit analog points, but does not give you control over which Modbus registers are assigned to which DNP3 points. Use automatic address mapping if you want to assign a large contiguous block of Modbus registers to DNP3 points and do not need to see which Modbus address is assigned to a particular DNP3 point.
The value of system point 58501 determines which address mapping method is used
The table below summarizes the data types that can be assigned to each point type in SCADAPack E Configurator when customized address mapping is used.
To assign Modbus registers to DNP3 points and view the mapping
|DNP3 Point Type
||Supported Modbus Data Types
|Analog points are one of the following:
- A signed quantity up to 32 bits.
- A floating point quantity (32-bit REAL).
The UDINT data type is not supported because an unsigned 32-bit quantity does not fit inside a signed 32-bit quantity. This is because a signed 32-bit quantity reserves 1 bit for the plus or minus sign.
Although the UDINT data type is not supported in SCADAPack E Configurator, there are two alternate ways to support 32-bit UDINT data types for analog points. For details, see Method 1 and 2 below.
||Binary points are packed into 8-bit values where the least significant bit represents low discrete numbers per Modbus FC=01.
|Counter points are unsigned quantities up to 32 bits.
INT and DINT data types are not supported because signed numbers do not fit inside unsigned quantities.
1. Verify that you are using SCADAPack E Configurator 8.11.1 or greater and that firmware 8.11.1 or greater is installed on the SCADAPack E. Perform, a refresh on the status page while connected the the RTU and check the "About" dialog box of the software
2. Verify that system point 58501 is NOT set to 0.
3. In SCADAPack E Configurator, set the Modbus Slave/Server method to either 5 digit or 6 digit addressing
4. In SCADAPack E Configurator, use the Modbus Slave tab on the point configuration form to assign Modbus registers to DNP3 points.
5. In order for the SCADAPack E to communicate to a Modbus Master, communication port(s) needs to be configured. On the Modbus Slave page. Configure the Modbus RTU address and/or enable Modbus/TCP Server and identifier (The default Modbus TCP port number 502 will be set by default).
6. If using a serial port, at least one of the serial ports needs to be configured for Modbus Slave. Configure this setting on the Ports page along with baud rate and mode settings.
The automatic method is the legacy method and is on by default. Information on how to configure 32bit mapping and the mapping structure can be found in the technical help manuals installed with SCADAPack E Configurator